re PR tree-optimization/57326 (Piecewise folding of operations on PHI nodes)

2016-08-12  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/57326
	* tree-ssa-pre.c (fully_constant_expression): Handle simplification
	returning an SSA name.
	(phi_translate_1): When fully_constant_expression returns a NAME
	make sure we have a leader for it.

	* gcc.dg/tree-ssa/ssa-pre-32.c: New testcase.
	* gcc.dg/tree-ssa/loadpre14.c: Adjust.
	* gcc.dg/tree-ssa/pr35287.c: Likewise.
	* gcc.target/i386/pr45685.c: Likewise.
	* gcc.dg/tree-ssa/predcom-1.c: Disable PRE.
	* gcc.dg/tree-ssa/predcom-2.c: Likewise.
	* gcc.dg/tree-ssa/predcom-3.c: Likewise.
	* gcc.dg/tree-ssa/ssa-sink-10.c: Likewise.
	* gfortran.dg/pr34163.f90: Likewise.

From-SVN: r239414

12 files changed, 64 insertions, 19 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 14f95cf..355f80d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2016-08-12  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57326
+	* tree-ssa-pre.c (fully_constant_expression): Handle simplification
+	returning an SSA name.
+	(phi_translate_1): When fully_constant_expression returns a NAME
+	make sure we have a leader for it.
+
 2016-08-12  Martin Liska  <mliska@suse.cz>
 
 	    Adam Fineman  <afineman@afineman.com>
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7700cec..1691c25 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,16 @@
+2016-08-12  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57326
+	* gcc.dg/tree-ssa/ssa-pre-32.c: New testcase.
+	* gcc.dg/tree-ssa/loadpre14.c: Adjust.
+	* gcc.dg/tree-ssa/pr35287.c: Likewise.
+	* gcc.target/i386/pr45685.c: Likewise.
+	* gcc.dg/tree-ssa/predcom-1.c: Disable PRE.
+	* gcc.dg/tree-ssa/predcom-2.c: Likewise.
+	* gcc.dg/tree-ssa/predcom-3.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-sink-10.c: Likewise.
+	* gfortran.dg/pr34163.f90: Likewise.
+
 2016-08-12  Martin Liska  <mliska@suse.cz>
 
 	* g++.dg/gcov/gcov-16.C: New test.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/loadpre14.c b/gcc/testsuite/gcc.dg/tree-ssa/loadpre14.c
index 989d933..456c89f 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/loadpre14.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/loadpre14.c
@@ -6,7 +6,8 @@ int foo(type *a, int argc)
   type c = {0, 1};
   int d, e;
 
-  /* Should be able to eliminate the second load of *a along the main path. */
+  /* Should be able to eliminate the second load of *a and the add of zero
+     along the main path. */
   d = (*a)[0];
   if (argc)
     {
@@ -15,4 +16,4 @@ int foo(type *a, int argc)
   e = (*a)[0];
   return d + e;
 }
-/* { dg-final { scan-tree-dump-times "Eliminated: 1" 1 "pre"} } */
+/* { dg-final { scan-tree-dump-times "Eliminated: 2" 1 "pre"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr35287.c b/gcc/testsuite/gcc.dg/tree-ssa/pr35287.c
index b091ba8..f7cc5c0 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr35287.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr35287.c
@@ -10,5 +10,6 @@ int foo(int p)
   return (*gp + t);
 }
 
-/* We will eliminate one load of gp and one indirect load of *gp. */
-/* { dg-final { scan-tree-dump-times "Eliminated: 2" 1 "pre"} } */
+/* We will eliminate one load of gp and one indirect load of *gp and
+   the add of zero. */
+/* { dg-final { scan-tree-dump-times "Eliminated: 3" 1 "pre"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/predcom-1.c b/gcc/testsuite/gcc.dg/tree-ssa/predcom-1.c
index 062b3da..4bc2ea5 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/predcom-1.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/predcom-1.c
@@ -1,6 +1,6 @@
 /* { dg-do compile } */
 /* { dg-do run } */
-/* { dg-options "-O2 -funroll-loops --param max-unroll-times=8 -fpredictive-commoning -fdump-tree-pcom-details" } */
+/* { dg-options "-O2 -funroll-loops --param max-unroll-times=8 -fpredictive-commoning -fdump-tree-pcom-details -fno-tree-pre" } */
 
 void abort (void);
 
@@ -45,6 +45,6 @@ int main(void)
 /* Verify that both loops were transformed and unrolled.  */
 /* { dg-final { scan-tree-dump-times "Unrolling 2 times." 2 "pcom"} } */
 
-/* Also check that we undid the transformation previously made by PRE.  */
-/* { dg-final { scan-tree-dump-times "looparound ref" 1 "pcom"} } */
-
+/* Also check that we undid the transformation previously made by PRE.
+   ???  PRE now does the predictive commoning in count_averages.  */
+/* dg-final { scan-tree-dump-times "looparound ref" 1 "pcom" } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/predcom-2.c b/gcc/testsuite/gcc.dg/tree-ssa/predcom-2.c
index 0d92f8e..d8fe51c 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/predcom-2.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/predcom-2.c
@@ -1,5 +1,5 @@
 /* { dg-do run } */
-/* { dg-options "-O2 -funroll-loops --param max-unroll-times=8 -fpredictive-commoning -fdump-tree-pcom-details" } */
+/* { dg-options "-O2 -funroll-loops --param max-unroll-times=8 -fpredictive-commoning -fdump-tree-pcom-details -fno-tree-pre" } */
 
 void abort (void);
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/predcom-3.c b/gcc/testsuite/gcc.dg/tree-ssa/predcom-3.c
index bfddb79..1174cd1 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/predcom-3.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/predcom-3.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -funroll-loops --param max-unroll-times=8 -fpredictive-commoning -fdump-tree-pcom-details" } */
+/* { dg-options "-O2 -funroll-loops --param max-unroll-times=8 -fpredictive-commoning -fdump-tree-pcom-details -fno-tree-pre" } */
 
 int a[1000], b[1000];
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-32.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-32.c
new file mode 100644
index 0000000..d9bd3a9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-32.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-pre" } */
+
+unsigned f(unsigned x, unsigned y, _Bool b)
+{
+#define m (b?-1:0)
+  return (x&m)|(y&~m);
+#undef m
+}
+
+/* { dg-final { scan-tree-dump "# prephitmp_\[0-9\]+ = PHI <\[xy\]_\[0-9\]+\\(D\\)\[^,\]*, \[xy\]_\[0-9\]+\\(D\\)" "pre" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c
index 4031e10..37e4d2f 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-sink-details" } */
+/* { dg-options "-O2 -fdump-tree-sink-details -fno-tree-pre" } */
 
 int x[1024], y[1024], z[1024], w[1024];
 void foo (void)
diff --git a/gcc/testsuite/gcc.target/i386/pr45685.c b/gcc/testsuite/gcc.target/i386/pr45685.c
index 93c6686..f9ed973 100644
--- a/gcc/testsuite/gcc.target/i386/pr45685.c
+++ b/gcc/testsuite/gcc.target/i386/pr45685.c
@@ -36,4 +36,4 @@ int summation_helper_2(int64_t* products, uint64_t count)
 	return s;
 }
 
-/* { dg-final { scan-assembler-times "cmov" 4 } } */
+/* { dg-final { scan-assembler-times "cmov" 6 } } */
diff --git a/gcc/testsuite/gfortran.dg/pr34163.f90 b/gcc/testsuite/gfortran.dg/pr34163.f90
index 1c94896..5ce8d00 100644
--- a/gcc/testsuite/gfortran.dg/pr34163.f90
+++ b/gcc/testsuite/gfortran.dg/pr34163.f90
@@ -1,5 +1,5 @@
 ! { dg-do compile }
-! { dg-options "-O2 -fpredictive-commoning -fdump-tree-pcom-details" }
+! { dg-options "-O2 -fno-tree-pre -fpredictive-commoning -fdump-tree-pcom-details" }
 subroutine trisolve2(x,i1,i2,nxyz)
 integer :: nxyz
 real,dimension(nxyz):: au1
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index c2c7495..edc3fdf 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -1201,7 +1201,7 @@ get_or_alloc_expr_for (tree t)
 }
 
 /* Return the folded version of T if T, when folded, is a gimple
-   min_invariant.  Otherwise, return T.  */
+   min_invariant or an SSA name.  Otherwise, return T.  */
 
 static pre_expr
 fully_constant_expression (pre_expr e)
@@ -1218,10 +1218,8 @@ fully_constant_expression (pre_expr e)
 	  return e;
 	if (is_gimple_min_invariant (res))
 	  return get_or_alloc_expr_for_constant (res);
-	/* We might have simplified the expression to a
-	   SSA_NAME for example from x_1 * 1.  But we cannot
-	   insert a PHI for x_1 unconditionally as x_1 might
-	   not be available readily.  */
+	if (TREE_CODE (res) == SSA_NAME)
+	  return get_or_alloc_expr_for_name (res);
 	return e;
       }
     case REFERENCE:
@@ -1464,7 +1462,20 @@ phi_translate_1 (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2,
 	    constant = fully_constant_expression (expr);
 	    PRE_EXPR_NARY (expr) = nary;
 	    if (constant != expr)
-	      return constant;
+	      {
+		/* For non-CONSTANTs we have to make sure we can eventually
+		   insert the expression.  Which means we need to have a
+		   leader for it.  */
+		if (constant->kind != CONSTANT)
+		  {
+		    unsigned value_id = get_expr_value_id (constant);
+		    constant = find_leader_in_sets (value_id, set1, set2);
+		    if (constant)
+		      return constant;
+		  }
+		else
+		  return constant;
+	      }
 
 	    tree result = vn_nary_op_lookup_pieces (newnary->length,
 						    newnary->opcode,