From 9aa610f489ae0e22bc87952d404ae334b1e68573 Mon Sep 17 00:00:00 2001
From: Stephen Williams <steve@icarus.com>
Date: Wed, 28 May 2008 08:47:28 -0700
Subject: [PATCH] Fix handling of 32bit IMM in %addi on 32bit machines

The handling of immediate add used to do 16bits at a time. When it went
up to 32bits, the need to work in chunks vanished, but the chunk handling
was still there, this time shifting by 32, which causes problems on 32bit
machines. Simplify the %addi handling to avoid this.
---
 tgt-vvp/eval_expr.c | 74 +++++++++++++++++++++++++++++++--------------
 1 file changed, 52 insertions(+), 22 deletions(-)

diff --git a/tgt-vvp/eval_expr.c b/tgt-vvp/eval_expr.c
index e1fb2013c..3bcbf2717 100644
--- a/tgt-vvp/eval_expr.c
+++ b/tgt-vvp/eval_expr.c
@@ -1197,23 +1197,50 @@ static struct vector_info draw_add_immediate(ivl_expr_t le,
 
       imm = get_number_immediate(re);
 
-	/* Now generate enough %addi instructions to add the entire
-	   immediate value to the destination. The adds are done IMM_WID
-	   bits at a time, but +1 bits are done to push the carry into
-	   the higher bits if needed. */
-      { unsigned base;
-        for (base = 0 ;  base < lv.wid ;  base += IMM_WID) {
-	      unsigned long tmp = imm & 0xffffffffUL;
-	      unsigned add_wid = lv.wid - base;
+	/* This shouldn't generally happen, because the elaborator
+	   should take care of simple constant propagation like this,
+	   but it doesn't have to and it is easy to catch here. */
+      if (imm == 0)
+	    return lv;
 
-	      imm >>= IMM_WID;
+      switch (lv.base) {
+	  case 0: /* Left expression is 0. */
+	    lv.base = allocate_vector(wid);
+	    if (lv.base == 0) {
+		  fprintf(stderr, "%s:%u: vvp.tgt error: "
+			  "Unable to allocate %u thread bits "
+			  "for result of addition.\n",
+			  ivl_expr_file(re), ivl_expr_lineno(re), wid);
+		  vvp_errors += 1;
+	    }
+	    fprintf(vvp_out, "   %%movi %u, %lu %u;\n", lv.base, imm, wid);
+	    break;
 
-	      fprintf(vvp_out, "    %%addi %u, %lu, %u;\n",
-		      lv.base+base, tmp, add_wid);
+	  case 1: /* Left expression is 1...1 (i.e. -1) */
+	    imm -= 1;
+	    if (imm == 0) {
+		  lv.base = 0;
+	    } else {
+		  lv.base = allocate_vector(wid);
+		  if (lv.base == 0) {
+			fprintf(stderr, "%s:%u: vvp.tgt error: "
+				"Unable to allocate %u thread bits "
+				"for result of addition.\n",
+				ivl_expr_file(re), ivl_expr_lineno(re), wid);
+			vvp_errors += 1;
+		  }
+		  fprintf(vvp_out, "   %%movi %u, %lu %u;\n", lv.base, imm, wid);
+	    }
+	    break;
 
-	      if (imm == 0)
-		    break;
-	}
+	  case 2: /* Left expression is X or Z */
+	  case 3:
+	    lv.base = 2;
+	    break;
+
+	  default: /* The regular case. */
+	    fprintf(vvp_out, "   %%addi %u, %lu, %u;\n", lv.base, imm, wid);
+	    break;
       }
 
       return lv;
@@ -1234,7 +1261,8 @@ static struct vector_info draw_sub_immediate(ivl_expr_t le,
       assert(lv.wid == wid);
 
       imm = get_number_immediate(re);
-      assert( (imm & ~0xffffffffUL) == 0 );
+      if (imm == 0)
+	    return lv;
 
       switch (lv.base) {
 	  case 0:
@@ -1248,21 +1276,21 @@ static struct vector_info draw_sub_immediate(ivl_expr_t le,
 		  vvp_errors += 1;
 	    }
 
-	    fprintf(vvp_out, "    %%mov %u, %u, %u;\n", tmp, lv.base, wid);
+	    fprintf(vvp_out, "   %%mov %u, %u, %u;\n", tmp, lv.base, wid);
 	    lv.base = tmp;
-	    fprintf(vvp_out, "    %%subi %u, %lu, %u;\n", lv.base, imm, wid);
-	    return lv;
+	    fprintf(vvp_out, "   %%subi %u, %lu, %u;\n", lv.base, imm, wid);
+	    break;
 
 	  case 2:
 	  case 3:
 	    lv.base = 2;
-	    return lv;
+	    break;
 
 	  default:
-	    fprintf(vvp_out, "    %%subi %u, %lu, %u;\n", lv.base, imm, wid);
+	    fprintf(vvp_out, "   %%subi %u, %lu, %u;\n", lv.base, imm, wid);
+	    break;
       }
 
-
       return lv;
 }
 
@@ -1277,8 +1305,10 @@ static struct vector_info draw_mul_immediate(ivl_expr_t le,
       assert(lv.wid == wid);
 
       imm = get_number_immediate(re);
+      if (imm == 0)
+	    return lv;
 
-      fprintf(vvp_out, "    %%muli %u, %lu, %u;\n", lv.base, imm, lv.wid);
+      fprintf(vvp_out, "   %%muli %u, %lu, %u;\n", lv.base, imm, lv.wid);
 
       return lv;
 }