From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 19 Nov 2024 09:25:04 +0000 (+0100)
Subject: bitintlower: Handle EXACT_DIV_EXPR like TRUNC_DIV_EXPR in bitint lowering [PR117571]
X-Git-Tag: basepoints/gcc-16~4113
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=758d2b3d3e28c831c79f5c18727d149c81896434;p=thirdparty%2Fgcc.git

bitintlower: Handle EXACT_DIV_EXPR like TRUNC_DIV_EXPR in bitint lowering [PR117571]

r15-4601 added match.pd simplification of some TRUNC_DIV_EXPR expressions
into EXACT_DIV_EXPR, so bitintlower can now encounter even those.
From bitint lowering POV the fact that the division will be exact
doesn't matter, we still need to call at runtime the __divmodbitint4
API and it wouldn't simplify there anything to know it is exact if
we duplicated that, so the following patch lowers EXACT_DIV_EXPR exactly
as TRUNC_DIV_EXPR.

I think we don't need to backport this unless something introduces
EXACT_DIV_EXPR on BITINT_TYPEd expressions on the 14 branch as well.

2024-11-19  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/117571
	* gimple-lower-bitint.cc (bitint_large_huge::lower_muldiv_stmt,
	bitint_large_huge::lower_stmt, stmt_needs_operand_addr,
	build_bitint_stmt_ssa_conflicts, gimple_lower_bitint): Handle
	EXACT_DIV_EXPR like TRUNC_DIV_EXPR.

	* gcc.dg/bitint-114.c: New test.
---

diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc
index 1d1e300643c7..6fc425375b12 100644
--- a/gcc/gimple-lower-bitint.cc
+++ b/gcc/gimple-lower-bitint.cc
@@ -3597,6 +3597,7 @@ bitint_large_huge::lower_muldiv_stmt (tree obj, gimple *stmt)
       insert_before (g);
       break;
     case TRUNC_DIV_EXPR:
+    case EXACT_DIV_EXPR:
       g = gimple_build_call_internal (IFN_DIVMODBITINT, 8,
 				      lhs, build_int_cst (sitype, prec),
 				      null_pointer_node,
@@ -5560,6 +5561,7 @@ bitint_large_huge::lower_stmt (gimple *stmt)
 		return;
 	      case MULT_EXPR:
 	      case TRUNC_DIV_EXPR:
+	      case EXACT_DIV_EXPR:
 	      case TRUNC_MOD_EXPR:
 		lower_muldiv_stmt (lhs, g);
 		goto handled;
@@ -5694,6 +5696,7 @@ bitint_large_huge::lower_stmt (gimple *stmt)
 	return;
       case MULT_EXPR:
       case TRUNC_DIV_EXPR:
+      case EXACT_DIV_EXPR:
       case TRUNC_MOD_EXPR:
 	lower_muldiv_stmt (NULL_TREE, stmt);
 	return;
@@ -5740,6 +5743,7 @@ stmt_needs_operand_addr (gimple *stmt)
       {
       case MULT_EXPR:
       case TRUNC_DIV_EXPR:
+      case EXACT_DIV_EXPR:
       case TRUNC_MOD_EXPR:
       case FLOAT_EXPR:
 	return true;
@@ -5931,6 +5935,7 @@ build_bitint_stmt_ssa_conflicts (gimple *stmt, live_track *live,
 		{
 		case MULT_EXPR:
 		case TRUNC_DIV_EXPR:
+		case EXACT_DIV_EXPR:
 		case TRUNC_MOD_EXPR:
 		  muldiv_p = true;
 		default:
@@ -6174,6 +6179,7 @@ gimple_lower_bitint (void)
 		break;
 	      case MULT_EXPR:
 	      case TRUNC_DIV_EXPR:
+	      case EXACT_DIV_EXPR:
 	      case TRUNC_MOD_EXPR:
 		if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (s))
 		  {
@@ -6455,6 +6461,7 @@ gimple_lower_bitint (void)
 			switch (gimple_assign_rhs_code (use_stmt))
 			  {
 			  case TRUNC_DIV_EXPR:
+			  case EXACT_DIV_EXPR:
 			  case TRUNC_MOD_EXPR:
 			  case FLOAT_EXPR:
 			    /* For division, modulo and casts to floating
@@ -6568,6 +6575,7 @@ gimple_lower_bitint (void)
 		  case RSHIFT_EXPR:
 		  case MULT_EXPR:
 		  case TRUNC_DIV_EXPR:
+		  case EXACT_DIV_EXPR:
 		  case TRUNC_MOD_EXPR:
 		  case FIX_TRUNC_EXPR:
 		  case REALPART_EXPR:
diff --git a/gcc/testsuite/gcc.dg/bitint-114.c b/gcc/testsuite/gcc.dg/bitint-114.c
new file mode 100644
index 000000000000..27db4ac28af4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-114.c
@@ -0,0 +1,23 @@
+/* PR middle-end/117571 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-O2" } */
+
+#if __BITINT_MAXWIDTH__ >= 255
+_BitInt(255) b;
+
+_BitInt(255)
+foo ()
+{
+  return (b << 10) / 2;
+}
+#endif
+
+#if __BITINT_MAXWIDTH__ >= 8192
+_BitInt(8192) c;
+
+_BitInt(8192)
+bar ()
+{
+  return (c << 1039) / 0x20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000wb;
+}
+#endif