From: Richard Biener <rguenther@suse.de>
Date: Wed, 16 Nov 2022 14:27:13 +0000 (+0100)
Subject: tree-optimization/107686 - fix bitfield ref through vec_unpack optimization
X-Git-Tag: release-12.2.mpacbti-rel1~218
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=232305bd0c8dd37b17b815864e730aa630714606;p=thirdparty%2Fgcc.git

tree-optimization/107686 - fix bitfield ref through vec_unpack optimization

The following propely restricts the bitfield access to integral types
when we look through VEC_UNPACK with the intent to emit a widening
conversion.

	PR tree-optimization/107686
	* tree-ssa-forwprop.cc (optimize_vector_load): Restrict
	VEC_UNPACK support to integral typed bitfield refs.

	* gcc.dg/pr107686.c: New testcase.

(cherry picked from commit 246bbdaa5f536b7a199dda9860c473137f40d622)
---

diff --git a/gcc/testsuite/gcc.dg/pr107686.c b/gcc/testsuite/gcc.dg/pr107686.c
new file mode 100644
index 000000000000..2378103c5553
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr107686.c
@@ -0,0 +1,16 @@
+/* { dg-do compile { target { dfp && longlong64 } } } */
+/* { dg-options "-O" } */
+/* { dg-additional-options "-mavx2" { target x86_64-*-* i?86-*-* } } */
+
+typedef _Decimal64 __attribute__((__vector_size__ (64))) D;
+typedef __INT32_TYPE__ __attribute__((__vector_size__ (32))) U;
+typedef __INT64_TYPE__ __attribute__((__vector_size__ (64))) V;
+
+U u;
+D d;
+
+void
+foo (void)
+{
+  d = d < (D) __builtin_convertvector (u, V);
+}
diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index 484491fa1c50..260d5dac83bc 100644
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -3118,7 +3118,11 @@ optimize_vector_load (gimple_stmt_iterator *gsi)
 	      && (def == lhs
 		  || (known_eq (bit_field_size (use_rhs), def_eltsize)
 		      && constant_multiple_p (bit_field_offset (use_rhs),
-					      def_eltsize))))
+					      def_eltsize)
+		      /* We can simulate the VEC_UNPACK_{HI,LO}_EXPR
+			 via a NOP_EXPR only for integral types.
+			 ???  Support VEC_UNPACK_FLOAT_{HI,LO}_EXPR.  */
+		      && INTEGRAL_TYPE_P (TREE_TYPE (use_rhs)))))
 	    {
 	      bf_stmts.safe_push (use_stmt);
 	      continue;