diff mbox series

Fix ipa-modref pure/const discovery

Message ID 20211112130315.GO17431@kam.mff.cuni.cz
State Committed
Commit 1b62cddcf091fb8cadf575246a7d3ff778650a6b
Headers
Series Fix ipa-modref pure/const discovery |

Commit Message

Jan Hubicka Nov. 12, 2021, 1:03 p.m. UTC 
  Hi,
this patch fixes bug I introduced while breaking up the bigger change.
We currently can not use pure/const to discover looping pures&const
since lack of global memory writes/stores does not imply we can CSE on
the function.  THis is witnessed by testsuite doing volatile asm
or also can happen if i.e. function returns result of malloc.

I have followup patch to add the analysis, but will first look into
current ICE of ltobootstrap.

Bootstrapped/regtested x86_64-linux, comitted.
	PR ipa/103200
	* ipa-modref.c (analyze_function, modref_propagate_in_scc): Do
	not mark pure/const function if there are side-effects.
diff mbox series

Patch

diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index 72006251f29..44b3427a202 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -2790,7 +2790,8 @@  analyze_function (function *f, bool ipa)
 
   if (!ipa && flag_ipa_pure_const)
     {
-      if (!summary->stores->every_base && !summary->stores->bases)
+      if (!summary->stores->every_base && !summary->stores->bases
+	  && !summary->side_effects)
 	{
 	  if (!summary->loads->every_base && !summary->loads->bases)
 	    fixup_cfg = ipa_make_function_const
@@ -4380,7 +4381,8 @@  modref_propagate_in_scc (cgraph_node *component_node)
 	modref_summary_lto *summary_lto = summaries_lto
 					  ? summaries_lto->get (cur)
 					  : NULL;
-	if (summary && !summary->stores->every_base && !summary->stores->bases)
+	if (summary && !summary->stores->every_base && !summary->stores->bases
+	    && !summary->side_effects)
 	  {
 	    if (!summary->loads->every_base && !summary->loads->bases)
 	      pureconst |= ipa_make_function_const
@@ -4390,7 +4392,7 @@  modref_propagate_in_scc (cgraph_node *component_node)
 		     (cur, summary->side_effects, false);
 	  }
 	if (summary_lto && !summary_lto->stores->every_base
-	    && !summary_lto->stores->bases)
+	    && !summary_lto->stores->bases && !summary_lto->side_effects)
 	  {
 	    if (!summary_lto->loads->every_base && !summary_lto->loads->bases)
 	      pureconst |= ipa_make_function_const