Fix PR80237

Message ID alpine.LSU.2.20.1704211015520.24645@zhemvz.fhfr.qr
State New
Headers show

Commit Message

Richard Biener April 21, 2017, 8:16 a.m.
This fixes a missed PRE which causes a missed tailcall.

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

Richard.

2017-04-21  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/80237
	* tree-ssa-pre.c (find_leader_in_sets): Add third set argument,
	defaulted to NULL.
	(phi_translate_1): Also allow a leader in AVAIL_OUT of pred
	for a simplified result.

	* gcc.dg/tree-ssa/tailcall-9.c: New testcase.
	* gcc.dg/tree-ssa/ldist-pr45948.c: Remove undefined behavior,
	adjust expected optimizations.

Patch

Index: gcc/testsuite/gcc.dg/tree-ssa/tailcall-9.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/tailcall-9.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/tailcall-9.c	(working copy)
@@ -0,0 +1,20 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-tailc-details" } */
+
+__attribute__((noinline))
+static float f(float x)
+{
+  return x*x;
+}
+
+static double g(float x)
+{
+  return x>0 ? f(x) : x+1.0;
+}
+
+float foo(float x)
+{
+  return g(x);
+}
+
+/* { dg-final { scan-tree-dump "Found tail call" "tailc" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/ldist-pr45948.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/ldist-pr45948.c	(revision 246533)
+++ gcc/testsuite/gcc.dg/tree-ssa/ldist-pr45948.c	(working copy)
@@ -1,14 +1,16 @@ 
 /* { dg-do compile } */
-/* { dg-options "-O2 -ftree-loop-distribution -ftree-loop-distribute-patterns -fdump-tree-ldist-details" } */
+/* { dg-options "-O2 -ftree-loop-distribution -ftree-loop-distribute-patterns -fdump-tree-ldist-details -fdump-tree-optimized" } */
 
 extern void bar(int);
 
 void
-foo (int i, int n)
+foo (unsigned i, unsigned n)
 {
   int a[30];
   int b[30];
-  for (; i < n; i++)
+  if (n == 0)
+    return;
+  for (i=0; i < n; i++)
     a[i] = b[i] = 0;
 
   while (1)
@@ -16,7 +18,9 @@  foo (int i, int n)
       bar (a[i - 1]);
 }
 
-/* We should apply loop distribution and generate 2 memset (0).  */
+/* We should apply loop distribution and generate 1 memset (0).  PRE optimizes
+   away a[] completely.  */
 
-/* { dg-final { scan-tree-dump "distributed: split to 0 loops and 2 library calls" "ldist" } } */
-/* { dg-final { scan-tree-dump-times "generated memset zero" 2 "ldist" } } */
+/* { dg-final { scan-tree-dump "distributed: split to 0 loops and 1 library calls" "ldist" } } */
+/* { dg-final { scan-tree-dump-times "generated memset zero" 1 "ldist" } } */
+/* { dg-final { scan-tree-dump-times "int a" 0 "optimized" } } */
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c	(revision 247024)
+++ gcc/tree-ssa-pre.c	(working copy)
@@ -1313,17 +1313,20 @@  translate_vuse_through_block (vec<vn_ref
 }
 
 /* Like bitmap_find_leader, but checks for the value existing in SET1 *or*
-   SET2.  This is used to avoid making a set consisting of the union
-   of PA_IN and ANTIC_IN during insert.  */
+   SET2 *or* SET3.  This is used to avoid making a set consisting of the union
+   of PA_IN and ANTIC_IN during insert and phi-translation.  */
 
 static inline pre_expr
-find_leader_in_sets (unsigned int val, bitmap_set_t set1, bitmap_set_t set2)
+find_leader_in_sets (unsigned int val, bitmap_set_t set1, bitmap_set_t set2,
+		     bitmap_set_t set3 = NULL)
 {
   pre_expr result;
 
   result = bitmap_find_leader (set1, val);
   if (!result && set2)
     result = bitmap_find_leader (set2, val);
+  if (!result && set3)
+    result = bitmap_find_leader (set3, val);
   return result;
 }
 
@@ -1478,7 +1481,8 @@  phi_translate_1 (pre_expr expr, bitmap_s
 		    else
 		      {
 			unsigned value_id = get_expr_value_id (constant);
-			constant = find_leader_in_sets (value_id, set1, set2);
+			constant = find_leader_in_sets (value_id, set1, set2,
+							AVAIL_OUT (pred));
 			if (constant)
 			  return constant;
 		      }