From: Andrew Pinski <apinski@marvell.com>
Date: Sun, 24 Sep 2023 04:53:09 +0000 (-0700)
Subject: Fix PR 110386: backprop vs ABSU_EXPR
X-Git-Tag: basepoints/gcc-15~5890
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2bbac12ea7bd8a3eef5382e1b13f6019df4ec03f;p=thirdparty%2Fgcc.git

Fix PR 110386: backprop vs ABSU_EXPR

The issue here is that when backprop tries to go
and strip sign ops, it skips over ABSU_EXPR but
ABSU_EXPR not only does an ABS, it also changes the
type to unsigned.
Since strip_sign_op_1 is only supposed to strip off
sign changing operands and not ones that change types,
removing ABSU_EXPR here is correct. We don't handle
nop conversions so this does cause any missed optimizations either.

OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR tree-optimization/110386

gcc/ChangeLog:

	* gimple-ssa-backprop.cc (strip_sign_op_1): Remove ABSU_EXPR.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/pr110386-1.c: New test.
	* gcc.c-torture/compile/pr110386-2.c: New test.
---

diff --git a/gcc/gimple-ssa-backprop.cc b/gcc/gimple-ssa-backprop.cc
index 65a65590017b..dcb15ed4f619 100644
--- a/gcc/gimple-ssa-backprop.cc
+++ b/gcc/gimple-ssa-backprop.cc
@@ -694,7 +694,6 @@ strip_sign_op_1 (tree rhs)
     switch (gimple_assign_rhs_code (assign))
       {
       case ABS_EXPR:
-      case ABSU_EXPR:
       case NEGATE_EXPR:
 	return gimple_assign_rhs1 (assign);
 
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c b/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
new file mode 100644
index 000000000000..4fcc977ad16f
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
@@ -0,0 +1,9 @@
+
+int f(int a)
+{
+        int c = c < 0 ? c : -c;
+        c = -c;
+        unsigned b =  c;
+        unsigned t = b*a;
+        return t*t;
+}
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c b/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c
new file mode 100644
index 000000000000..c60e1b6994b7
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-mavx" } */
+
+#include <immintrin.h>
+
+__m128i do_stuff(__m128i XMM0) {
+	__m128i ABS0 = _mm_abs_epi32(XMM0);
+	__m128i MUL0 = _mm_mullo_epi32(ABS0, XMM0);
+	__m128i MUL1 = _mm_mullo_epi32(MUL0, MUL0);
+	return MUL1;
+}