refactor sizing and truncation of integer literals

- use iverilog's -gstrict-expr-width throughout test suite
- add warnings for excess bits or padding zeroes in number literals
- add new --oversized-numbers parameter to retain support for unsized
  numbers wider than 32 bits
- localized use of oversized numbers to new truncate test suite which
  verifies the behavior of both modes, and compares against the known
  behavior of iverilog

CHANGELOG.md

@@ -1,5 +1,15 @@
 ## Unreleased
 
+* Explicitly-sized number literals with non-zero bits exceeding the given width
+  (e.g., `1'b11`, `3'sd8`, `2'o7`) are truncated and produce a warning, rather
+  than yielding a cryptic error
+* Unsized number literals exceeding the maximum width of 32 bits (e.g.,
+  `'h1_ffff_ffff`, `4294967296`) are truncated and produce a warning, rather
+  than being silently extended
+  * Support for unsized number literals exceeding the standard-imposed 32-bit
+    limit can be re-enabled with `--oversized-numbers`
+* Number literals with leading zeroes which extend beyond the width of the
+  literal (e.g., `1'b01`, `'h0_FFFF_FFFF`) now produce a warning
 * Non-positive integer size casts are now detected and forbidden
 * Negative indices in struct pattern literals are now detected and forbidden
 

README.md

@@ -101,6 +101,8 @@ Conversion:
                             'adjacent' to create a .v file next to each input;
                             use a path ending in .v to write to a file
 Other:
+     --oversized-numbers    Disable standard-imposed 32-bit limit on unsized
+                            number literals (e.g., 'h1_ffff_ffff, 4294967296)
      --help                 Display help message
      --version              Print version information
      --numeric-version      Print just the version number

src/Job.hs

@@ -43,6 +43,7 @@ data Job = Job
     , verbose :: Bool
     , write :: Write
     , writeRaw :: String
+    , oversizedNumbers :: Bool
     } deriving (Typeable, Data)
 
 version :: String
@@ -71,13 +72,17 @@ defaultJob = Job
         &= help ("How to write output; default is 'stdout'; use 'adjacent' to"
             ++ " create a .v file next to each input; use a path ending in .v"
             ++ " to write to a file")
+    , oversizedNumbers = nam_ "oversized-numbers"
+        &= help ("Disable standard-imposed 32-bit limit on unsized number"
+            ++ " literals (e.g., 'h1_ffff_ffff, 4294967296)")
+        &= groupname "Other"
     }
     &= program "sv2v"
     &= summary ("sv2v " ++ version)
     &= details [ "sv2v converts SystemVerilog to Verilog."
                , "More info: https://github.com/zachjs/sv2v"
                , "(C) 2019-2021 Zachary Snow, 2011-2015 Tom Hawkins" ]
-    &= helpArg [explicit, name "help", groupname "Other"]
+    &= helpArg [explicit, name "help"]
     &= versionArg [explicit, name "version"]
     &= verbosityArgs [ignore] [ignore]
     where

src/Language/SystemVerilog/AST/Number.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE TupleSections #-}
 {- sv2v
  - Author: Zachary Snow <zach@zachjs.com>
  -
@@ -22,36 +23,127 @@ import Data.Char (digitToInt, intToDigit, toLower)
 import Data.List (elemIndex)
 import Text.Read (readMaybe)
 
+{-# NOINLINE parseNumber #-}
+parseNumber :: Bool -> String -> (Number, String)
+parseNumber oversizedNumbers =
+    (parseNormalized oversizedNumbers) . normalizeNumber
+
 -- normalize the number first, making everything lowercase and removing
 -- visual niceties like spaces and underscores
-parseNumber :: String -> Number
-parseNumber = parseNumber' . map toLower . filter (not . isPad)
+normalizeNumber :: String -> String
+normalizeNumber = map toLower . filter (not . isPad)
     where isPad = flip elem "_ \n\t"
 
-parseNumber' :: String -> Number
-parseNumber' "'0" = UnbasedUnsized Bit0
-parseNumber' "'1" = UnbasedUnsized Bit1
-parseNumber' "'x" = UnbasedUnsized BitX
-parseNumber' "'z" = UnbasedUnsized BitZ
-parseNumber' str =
+-- truncate the given decimal number literal, if necessary
+validateDecimal :: Bool -> String -> Int -> Bool -> Integer -> (Number, String)
+validateDecimal oversizedNumbers str sz sg v
+    | sz < -32 && oversizedNumbers =
+        valid $ Decimal sz sg v
+    | sz < -32 =
+        addTruncateMessage str $
+        if sg && v' > widthMask 31
+            -- avoid zero-pad on signed decimals
+            then Based (-32) sg Hex v' 0
+            else Decimal (-32) sg v'
+    | sz > 0 && v > widthMask sz =
+        addTruncateMessage str $
+            Decimal sz sg v'
+    | otherwise =
+        valid $ Decimal sz sg v
+    where
+        v' = v .&. widthMask truncWidth
+        truncWidth = if sz < -32 then -32 else sz
+
+-- produce a warning message describing the applied truncation
+addTruncateMessage :: String -> Number -> (Number, String)
+addTruncateMessage orig trunc = (trunc, msg)
+    where
+        width = show $ numberBitLength trunc
+        bit = if width == "1" then "bit" else "bits"
+        msg = "Number literal " ++ orig ++ " exceeds " ++ width ++ " " ++ bit
+            ++ "; truncating to " ++ show trunc ++ "."
+
+-- when extending a wide unsized number, we use the bit width if the digits
+-- cover exactly that many bits, and add an extra 0 padding bit otherwise
+extendUnsizedBased :: Int -> Number -> Number
+extendUnsizedBased sizeByDigits n
+    | size > -32 || sizeByBits < 32 = n
+    | sizeByBits == sizeByDigits    = useWidth sizeByBits
+    | otherwise                     = useWidth $ sizeByBits + 1
+    where
+        Based size sg base vals knds = n
+        sizeByBits = fromIntegral $ max (bits vals) (bits knds)
+        useWidth sz = Based (negate sz) sg base vals knds
+
+-- truncate the given based number literal, if necessary
+validateBased :: String -> Int -> Int -> Number -> (Number, String)
+validateBased orig sizeIfPadded sizeByDigits n
+    -- more digits than the size would allow for, regardless of their values
+    | sizeIfPadded < sizeByDigits            = truncated
+    -- unsized literal with fewer than 32 bits
+    | 0 > size && size > -32                 = validated
+    -- no padding bits are present
+    | abs size >= sizeIfPadded               = validated
+    -- check the padding bits in the leading digit, if there are any
+    | all (isLegalPad sizethBit) paddingBits = validated
+    -- some of the padding bits aren't legal
+    | otherwise                              = truncated
+    where
+        Based size sg base vals knds = n
+        n' = Based size sg base' vals' knds'
+
+        validated = valid n
+        truncated = addTruncateMessage orig n'
+
+        -- checking padding bits
+        sizethBit = getBit $ abs size - 1
+        paddingBits = map getBit [abs size..sizeIfPadded - 1]
+        getBit = getVKBit vals knds
+
+        -- truncated the number, and selected a valid new base
+        vals' = vals .&. widthMask size
+        knds' = knds .&. widthMask size
+        base' = if size == -32 && baseSelect == Octal
+            then Binary
+            else baseSelect
+        baseSelect = selectBase base vals' knds'
+
+-- if the MSB post-truncation is X or Z, then any padding bits must match; if
+-- the MSB post-truncation is 0 or 1, then non-zero padding bits are forbidden
+isLegalPad :: Bit -> Bit -> Bool
+isLegalPad Bit1 = (== Bit0)
+isLegalPad bit = (== bit)
+
+parseNormalized :: Bool -> String -> (Number, String)
+parseNormalized _ "'0" = valid $ UnbasedUnsized Bit0
+parseNormalized _ "'1" = valid $ UnbasedUnsized Bit1
+parseNormalized _ "'x" = valid $ UnbasedUnsized BitX
+parseNormalized _ "'z" = valid $ UnbasedUnsized BitZ
+parseNormalized oversizedNumbers str =
     -- simple decimal number
     if maybeIdx == Nothing then
-        let n = readDecimal str
-        in Decimal (negate $ decimalSize True n) True n
+        let num = readDecimal str
+            sz = negate (decimalSize True num)
+        in decimal sz True num
     -- non-decimal based integral number
     else if maybeBase /= Nothing then
         let (values, kinds) = parseBasedDigits (baseSize base) digitsExtended
-        in Based size signed base values kinds
+            number = Based size signed base values kinds
+            sizeIfPadded = sizeDigits * bitsPerDigit
+            sizeByDigits = length digitsExtended * bitsPerDigit
+        in if oversizedNumbers && size < 0
+            then valid $ extendUnsizedBased sizeByDigits number
+            else validateBased str sizeIfPadded sizeByDigits number
     -- decimal X or Z literal
-    else if numDigits == 1 && elem leadDigit xzDigits then
-        let (vals, knds) = parseBasedDigits 2 $ replicate (abs size) leadDigit
-        in Based size signed Binary vals knds
+    else if numDigits == 1 && leadDigitIsXZ then
+        let vals = if elem leadDigit zDigits then widthMask size else 0
+            knds = widthMask size
+        in valid $ Based size signed Binary vals knds
     -- explicitly-based decimal number
     else
         let num = readDecimal digits
-        in if rawSize == 0
-            then Decimal (negate $ decimalSize signed num) signed num
-            else Decimal size signed num
+            sz = if rawSize == 0 then negate (decimalSize signed num) else size
+        in decimal sz signed num
     where
         -- pull out the components of the literals
         maybeIdx = elemIndex '\'' str
@@ -63,8 +155,9 @@ parseNumber' str =
         -- high-order X or Z is extended up to the size of the literal
         leadDigit = head digits
         numDigits = length digits
+        leadDigitIsXZ = elem leadDigit xzDigits
         digitsExtended =
-            if elem leadDigit xzDigits
+            if leadDigitIsXZ
                 then replicate (sizeDigits - numDigits) leadDigit ++ digits
                 else digits
 
@@ -84,12 +177,24 @@ parseNumber' str =
         size =
             if rawSize /= 0 then
                 rawSize
-            else if maybeBase /= Nothing then
-                negate $ bitsPerDigit * numDigits
-            else
+            else if maybeBase == Nothing || leadDigitIsXZ then
                 -32
+            else
+                negate $ min 32 $ bitsPerDigit * numDigits
         bitsPerDigit = bits $ baseSize base - 1
 
+        -- shortcut for decimal outputs
+        decimal :: Int -> Bool -> Integer -> (Number, String)
+        decimal = validateDecimal oversizedNumbers str
+
+-- shorthand denoting a valid number literal
+valid :: Number -> (Number, String)
+valid = (, "")
+
+-- mask with the lowest N bits set
+widthMask :: Int -> Integer
+widthMask pow = 2 ^ (abs pow) - 1
+
 -- read a simple unsigned decimal number
 readDecimal :: Read a => String -> a
 readDecimal str =
@@ -171,6 +276,16 @@ bitToVK Bit1 = (1, 0)
 bitToVK BitX = (0, 1)
 bitToVK BitZ = (1, 1)
 
+-- get the logical bit value at the given index in a (values, kinds) pair
+getVKBit :: Integer -> Integer -> Int -> Bit
+getVKBit v k i =
+    case (v .&. select, k .&. select) of
+        (0, 0) -> Bit0
+        (_, 0) -> Bit1
+        (0, _) -> BitX
+        (_, _) -> BitZ
+    where select = 2 ^ i
+
 data Base
     = Binary
     | Octal

src/Language/SystemVerilog/Parser.hs

@@ -22,6 +22,7 @@ data Config = Config
     , cfIncludePaths :: [FilePath]
     , cfSiloed :: Bool
     , cfSkipPreprocessor :: Bool
+    , cfOversizedNumbers :: Bool
     }
 
 -- parse CLI macro definitions into the internal macro environment format
@@ -48,7 +49,7 @@ parseFile :: Config -> FilePath -> ExceptT String IO (Config, AST)
 parseFile config path = do
     (config', contents) <- preprocessFile config path
     tokens <- liftEither $ runExcept $ lexStr contents
-    ast <- parse tokens
+    ast <- parse (cfOversizedNumbers config) tokens
     return (config', ast)
 
 -- preprocess an individual file, potentially updating the configuration

src/Language/SystemVerilog/Parser/Parse.y

@@ -19,6 +19,7 @@ module Language.SystemVerilog.Parser.Parse (parse) where
 import Control.Monad.Except
 import Control.Monad.State.Strict
 import Data.Maybe (catMaybes, fromMaybe)
+import System.IO (hPutStrLn, stderr)
 import Language.SystemVerilog.AST
 import Language.SystemVerilog.Parser.ParseDecl
 import Language.SystemVerilog.Parser.Tokens
@@ -1206,7 +1207,7 @@ Real :: { String }
   : real { tokenString $1 }
 
 Number :: { Number }
-  : number { parseNumber $ tokenString $1 }
+  : number {% readNumber (tokenPosition $1) (tokenString $1) }
 
 String :: { String }
   : string { tail $ init $ tokenString $1 }
@@ -1463,25 +1464,26 @@ join         : "join"         {} | error {% missingToken "join"         }
 data ParseData = ParseData
   { pPosition :: Position
   , pTokens :: [Token]
+  , pOversizedNumbers :: Bool
   }
 
 type ParseState = StateT ParseData (ExceptT String IO)
 
-parse :: [Token] -> ExceptT String IO AST
-parse [] = return []
-parse tokens =
+parse :: Bool -> [Token] -> ExceptT String IO AST
+parse _ [] = return []
+parse oversizedNumbers tokens =
   evalStateT parseMain initialState
   where
     position = tokenPosition $ head tokens
-    initialState = ParseData position tokens
+    initialState = ParseData position tokens oversizedNumbers
 
 positionKeep :: (Token -> ParseState a) -> ParseState a
 positionKeep cont = do
-  tokens <- gets pTokens
+  ParseData _ tokens oversizedNumbers <- get
   case tokens of
     [] -> cont TokenEOF
     tok : toks -> do
-      put $ ParseData (tokenPosition tok) toks
+      put $ ParseData (tokenPosition tok) toks oversizedNumbers
       cont tok
 
 parseErrorTok :: Token -> ParseState a
@@ -1672,4 +1674,12 @@ splitInit decl =
   (Variable d t ident a Nil, Just (LHSIdent ident, e))
   where Variable d t ident a e = decl
 
+readNumber :: Position -> String -> ParseState Number
+readNumber pos str = do
+  oversizedNumbers <- gets pOversizedNumbers
+  let (num, msg) = parseNumber oversizedNumbers str
+  when (not $ null msg) $ lift $ lift $
+    hPutStrLn stderr $ show pos ++ ": Warning: " ++ msg
+  return num
+
 }

src/sv2v.hs

@@ -80,6 +80,7 @@ main = do
             , cfIncludePaths     = incdir job
             , cfSiloed           = siloed job
             , cfSkipPreprocessor = skipPreprocessor job
+            , cfOversizedNumbers = oversizedNumbers job
             }
     result <- runExceptT $ parseFiles config (files job)
     case result of

test/basic/shift.sv

@@ -26,25 +26,5 @@ module top;
         `TEST(2, 1);
         `TEST(2, 2);
         `TEST(2, 3);
-
-        `TEST(-8589934592, 0);
-        `TEST(-8589934592, 1);
-        `TEST(-8589934592, 2);
-        `TEST(-8589934592, 3);
-
-        `TEST(-8589934593, 0);
-        `TEST(-8589934593, 1);
-        `TEST(-8589934593, 2);
-        `TEST(-8589934593, 3);
-
-        `TEST(8589934592, 0);
-        `TEST(8589934592, 1);
-        `TEST(8589934592, 2);
-        `TEST(8589934592, 3);
-
-        `TEST(8589934593, 0);
-        `TEST(8589934593, 1);
-        `TEST(8589934593, 2);
-        `TEST(8589934593, 3);
     end
 endmodule

test/core/cast.sv

@@ -29,10 +29,6 @@ module top;
         $display("%b", 32'(4));
         $display("%b", 33'(4));
         $display("%b", 33'(64'hFFFF_FFFF_FFFF_FFFF));
-        $display("%b", 32'(4294967296));
-        $display("%b", 33'(4294967296));
-        $display("%b", 32'(4294967297));
-        $display("%b", 33'(4294967297));
     end
 
     localparam bit foo = '0;

test/core/cast.v

@@ -32,10 +32,6 @@ module top;
         $display("%b", 32'd4);
         $display("%b", 33'd4);
         $display("%b", 33'h1_FFFF_FFFF);
-        $display("%b", 32'd0);
-        $display("%b", 33'd4294967296);
-        $display("%b", 32'd1);
-        $display("%b", 33'd4294967297);
     end
 
     localparam [0:0] foo = 0;

test/core/duplicate_genvar_shadow.v

@@ -1,9 +0,0 @@
-module top;
-    initial begin
-        $display("A %0d", 32);
-        $display("B %0d", 10);
-        $display("C %0d", 32);
-        $display("D %0d", 6);
-        $display("E %0d", 32);
-    end
-endmodule

test/core/sign_cast.sv

@@ -1,7 +1,9 @@
 module top;
     initial begin
-        $display(signed'(4294967295));
-        $display(unsigned'(4294967295));
+        $display(signed'(1'b1));
+        $display(unsigned'(1'sb1));
+        $display(signed'(1));
+        $display(unsigned'(1));
         $display(signed'(-1));
         $display(unsigned'(-1));
     end

test/core/sign_cast.v

@@ -1,7 +1,9 @@
 module top;
     initial begin
-        $display($signed(4294967295));
-        $display($unsigned(4294967295));
+        $display($signed(1'b1));
+        $display($unsigned(1'sb1));
+        $display($signed(1));
+        $display($unsigned(1));
         $display($signed(-1));
         $display($unsigned(-1));
     end

test/core/struct_array_tb.v

@@ -10,7 +10,7 @@ module top;
 
     initial begin
         $monitor("%d: %01b %04b %02b", select, a, b, c);
-        in = 'b01111011011011101111100111110111001010001011100110101000;
+        in = 56'b01111011011011101111100111110111001010001011100110101000;
         select = 0; #1;
         select = 1; #1;
         select = 2; #1;

test/lex/number.sv

@@ -15,13 +15,8 @@ module top;
         `TEST(1'SOZ) `TEST(2'SOZ) `TEST(3'SOZ) `TEST(7'SOZ) `TEST(8'SOZ) `TEST(9'SOZ) `TEST(9'SOZZ) `TEST(10'SOZZ)
 
         `TEST(1234_5678) `TEST('h1234_5678) `TEST('o1234_5677) `TEST('b0101_1100)
-        `TEST('d4294967295) `TEST('d4294967296) `TEST('d4294967297) `TEST('d4294967298) `TEST('d4294967299)
-        `TEST('d004294967295) `TEST('d004294967296) `TEST('d004294967297) `TEST('d004294967298) `TEST('d004294967299)
-
-        `TEST(4294967295) `TEST(4294967296) `TEST(4294967297) `TEST(4294967298) `TEST(4294967299)
-        `TEST(-4294967295) `TEST(-4294967297) `TEST(-4294967298) `TEST(-4294967299)
-        `TEST(-8589934593) `TEST(8589934592) `TEST(8589934593)
-        // iverlog does weird things with these: `TEST(-4294967296) `TEST(-8589934592)
+        `TEST('d4294967294) `TEST('d4294967295)
+        `TEST('d004294967294) `TEST('d004294967295)
 
         `TEST(659) `TEST('h 837FF) `TEST('o7460)
         `TEST(4'b1001) `TEST(5 'D 3) `TEST(3'b01x) `TEST(12'hx) `TEST(16'hz)
@@ -31,10 +26,9 @@ module top;
         `TEST(3'bx) `TEST(3'b1x) `TEST(3'bx1) `TEST('b1x) `TEST('bx1) `TEST(3'b0x1) `TEST(3'b0z1)
         `TEST('hf & 10'hf) `TEST(7'hf & 10'hf)
 
-        `TEST('b01xz01xz01xz01xz01xz01xz01xz01xz01xz) `TEST('b101xz01xz01xz01xz01xz01xz01xz01xz01xz)
         `TEST(36'b01xz01xz01xz01xz01xz01xz01xz01xz01xz) `TEST(37'b01xz01xz01xz01xz01xz01xz01xz01xz01xz)
         `TEST(36'sb01xz01xz01xz01xz01xz01xz01xz01xz01xz) `TEST(37'sb01xz01xz01xz01xz01xz01xz01xz01xz01xz)
-        `TEST('h01xz01xz) `TEST('h101xz01xz)
+        `TEST('h01xz01xz)
         `TEST(36'h01xz01xz) `TEST(37'h01xz01xz)
         `TEST(36'hb01xz01xz) `TEST(37'hb01xz01xz)
 

test/lib/functions.sh

@@ -24,12 +24,20 @@ simulate() {
         -Wno-portbind \
         -o $sim_prog \
         -g2005 \
+        -gstrict-expr-width \
         -DTEST_VCD="\"$sim_vcd_tmp\"" \
         -DTEST_TOP=$sim_top \
+        "$@" \
         $SCRIPT_DIR/tb_dumper.v \
-        "$@" 2>&1`
-    assertTrue "iverilog on $1 failed" $?
-    assertNull "iverilog emitted warnings:\n$iv_output" "$iv_output"
+        2>&1`
+    if [ $? -ne 0 ]; then
+        fail "iverilog on $1 failed:\n$iv_output"
+        return
+    elif [ "$EXPECT_IVERILOG_WARNINGS" != "0" ]; then
+        assertNull "iverilog on $1 emitted warnings:\n$iv_output" "$iv_output"
+    else
+        assertNotNull "iverilog on $1 did not emit any warnings" "$iv_output"
+    fi
     # run the simulation
     $sim_prog > $sim_log
     assertTrue "simulating $1 failed" $?

test/truncate/no_trunc.txt

@@ -0,0 +1,54 @@
+'dX
+'dZ
+'sdX
+'sdZ
+
+'b0
+'b1
+'bx
+'bz
+
+'sb0
+'sb1
+'sbx
+'sbz
+
+1'b0
+1'b1
+1'bx
+1'bz
+
+1'sb0
+1'sb1
+1'sbx
+1'sbz
+
+1'hX
+1'hZ
+2'hX
+2'hZ
+3'hX
+3'hZ
+4'hX
+4'hZ
+5'hX
+5'hZ
+
+1'oX
+1'oZ
+2'oX
+2'oZ
+3'oX
+3'oZ
+4'oX
+4'oZ
+
+1'sd1
+2'sd2
+2'sd3
+32'sd4294967294
+
+'o1xz01xz01xz
+'o2xz01xz01xz
+32'o1xz01xz01xz
+32'o2xz01xz01xz

test/truncate/run.sh

@@ -0,0 +1,85 @@
+#!/bin/bash
+
+testNumber() {
+    mode=$1
+    number=$2
+
+    ve=$SHUNIT_TMPDIR/ve.v
+    cs=$SHUNIT_TMPDIR/cs.v
+
+    ve_log=$ve.log
+    cs_log=$cs.log
+
+    # substitute the current number literal into a copy of the test template
+    sed -e "s/NUM/$number/" < template.v > $ve
+
+    # convert in strict mode
+    runAndCapture $ve
+    assertTrue "conversion should succeed" $result
+    assertNotNull "stdout should not be empty" "$stdout"
+    if [ $mode = no_trunc ]; then
+        assertNull "stderr should be empty:\n$stderr" "$stderr"
+    else
+        assertNotNull "stderr should not be empty" "$stderr"
+    fi
+
+    # convert result in strict mode
+    mv -f $SHUNIT_TMPDIR/stdout $cs
+    runAndCapture $cs
+    assertTrue "conversion should succeed" $result
+    assertNotNull "stdout should not be empty" "$stdout"
+    assertNull "stderr should be empty:\n$stderr" "$stderr"
+
+    # simulate and compare in strict mode
+    EXPECT_IVERILOG_WARNINGS=`[ $mode = trunc_ivl_warns ]; echo $?` \
+    simulate /dev/null $ve_log top $ve
+    simulate /dev/null $cs_log top $cs
+    output=`diff $ve_log $cs_log`
+    assertTrue "number literals differ:\n$output" $?
+
+    # convert in lax mode
+    runAndCapture --oversized-numbers $ve
+    assertTrue "conversion should succeed" $result
+    assertNotNull "stdout should not be empty" "$stdout"
+    if [ $mode = no_trunc ] || [[ ! "$number" =~ .\' ]]; then
+        assertNull "stderr should be empty:\n$stderr" "$stderr"
+    else
+        assertNotNull "stderr should not be empty" "$stderr"
+    fi
+
+    # convert result in lax mode
+    mv -f $SHUNIT_TMPDIR/stdout $cs
+    runAndCapture --oversized-numbers $cs
+    assertTrue "conversion should succeed" $result
+    assertNotNull "stdout should not be empty" "$stdout"
+    assertNull "stderr should be empty:\n$stderr" "$stderr"
+
+    # simulate and compare in lax mode
+    EXPECT_IVERILOG_WARNINGS=`[[ "$number" =~ .\' ]] && [ $mode = trunc_ivl_warns ]; echo $?` \
+    simulate /dev/null $ve_log top -gno-strict-expr-width $ve
+    simulate /dev/null $cs_log top -gno-strict-expr-width $cs
+    output=`diff $ve_log $cs_log`
+    assertTrue "number literals differ:\n$output" $?
+}
+
+addTest() {
+    mode=$1
+    number=$2
+    test="${mode}_${number//\'/_}"
+    eval "$test() { testNumber $mode \"$number\"; }"
+    suite_addTest $test
+}
+
+suite() {
+    modes=(no_trunc trunc_ivl_warns trunc_ivl_silent)
+    for mode in ${modes[@]}; do
+        while read number; do
+            [ -n "$number" ] && \
+                addTest $mode "$number"
+        done < $mode.txt
+    done
+}
+
+source ../lib/functions.sh
+
+. shunit2

test/truncate/template.v

@@ -0,0 +1,5 @@
+module top;
+    localparam X = NUM;
+    localparam [63:0] Y = X;
+    initial $display("%0d %b %b", $bits(X), X, Y);
+endmodule

test/truncate/trunc_ivl_silent.txt

@@ -0,0 +1,8 @@
+'h0_FFFF_FFFF
+'o00xz01xz01xz
+'o01xz01xz01xz
+'bz01xz01xz01xz01xz01xz01xz01xz01xz
+'hZ_ZZZZ_ZZZZ
+'hz01xz01xz
+4294967294
+4294967295

test/truncate/trunc_ivl_warns.txt

@@ -0,0 +1,59 @@
+1'b01
+1'b001
+1'bxx
+1'b0x
+
+1'd2
+1'sd2
+1'd3
+1'sd3
+3'sd8
+
+'b101xz01xz01xz01xz01xz01xz01xz01xz
+'bxz01xz01xz01xz01xz01xz01xz01xz01xz
+'b1xz01xz01xz01xz01xz01xz01xz01xz01xz
+
+32'bz01xz01xz01xz01xz01xz01xz01xz01xz
+32'bxz01xz01xz01xz01xz01xz01xz01xz01xz
+32'b1xz01xz01xz01xz01xz01xz01xz01xz01xz
+
+2'o4
+2'o7
+
+'h1_FFFF_FFFF
+'hF_FFFF_FFFF
+
+'o4xz01xz01xz
+'oz1xz01xz01xz
+
+'h101xz01xz
+'hxz01xz01xz
+'h0xz01xz01xz
+
+'d4294967296
+'d4294967297
+'d04294967296
+'d04294967297
+
+'d8589934590
+'d8589934591
+'d8589934592
+'d8589934593
+
+4294967296
+4294967297
+
+8589934590
+8589934591
+8589934592
+8589934593
+
+1'd111
+1'b111
+1'o111
+1'h111
+
+2'd111
+2'b111
+2'o111
+2'h111