diff mbox series

tree-optimization/100278 - handle mismatched code in TBAA adjust of PRE

Message ID nycvar.YFH.7.76.2104271029420.29927@elmra.sevgm.obk
State New
Headers show
Series tree-optimization/100278 - handle mismatched code in TBAA adjust of PRE | expand

Commit Message

Richard Biener April 27, 2021, 8:29 a.m. UTC 
PRE has code to adjust TBAA behavior for refs that expects the base
operation code to match.  The testcase shows a case where we have
a VAR_DECL vs. a MEM_REF so add code to give up in such cases.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed to trunk
sofar.

2021-04-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/100278
	* tree-ssa-pre.c (compute_avail): Give up when we cannot
	adjust TBAA beacuse of mismatching bases.

	* gcc.dg/tree-ssa/pr100278.c: New testcase.
---
 gcc/testsuite/gcc.dg/tree-ssa/pr100278.c | 17 +++++++++++++++++
 gcc/tree-ssa-pre.c                       | 10 ++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr100278.c
diff mbox series

Patch

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr100278.c b/gcc/testsuite/gcc.dg/tree-ssa/pr100278.c
new file mode 100644
index 00000000000..8d702284c3a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr100278.c
@@ -0,0 +1,17 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+void a()
+{
+#if defined __s390__
+  register int b asm("r5");
+#elif defined __x86_64__
+  register int b asm("eax");
+#else
+  volatile int b;
+#endif
+  if (b)
+    b = 1;
+  for (; b;)
+    ;
+}
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 2803b58430e..2d22535af87 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -4151,6 +4151,16 @@  compute_avail (void)
 		      if (ref->set == set
 			  || alias_set_subset_of (set, ref->set))
 			;
+		      else if (ref1->opcode != ref2->opcode
+			       || (ref1->opcode != MEM_REF
+				   && ref1->opcode != TARGET_MEM_REF))
+			{
+			  /* With mismatching base opcodes or bases
+			     other than MEM_REF or TARGET_MEM_REF we
+			     can't do any easy TBAA adjustment.  */
+			  operands.release ();
+			  continue;
+			}
 		      else if (alias_set_subset_of (ref->set, set))
 			{
 			  ref->set = set;