2017-04-25 Richard Biener <rguenther@suse.de>

	PR tree-optimization/80492
	* alias.c (compare_base_decls): Handle registers with asm
	specification conservatively.
	* tree-ssa-alias.c (decl_refs_may_alias_p): Handle
	compare_base_decls returning dont-know properly.

	* gcc.dg/pr80492.c: New testcase.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@247208 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2f4164737c11f5ed28e18b23d2a72d619beefe36..41567792b6bbb66b120b3bbe3c1658e6cdd66472 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2017-04-25  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/80492
+       * alias.c (compare_base_decls): Handle registers with asm
+       specification conservatively.
+       * tree-ssa-alias.c (decl_refs_may_alias_p): Handle
+       compare_base_decls returning dont-know properly.
+
 2017-04-25  Claudiu Zissulescu  <claziss@synopsys.com>
 
        * config/arc/arc.c (LEGITIMATE_OFFSET_ADDRESS_P): Delete macro.

diff --git a/gcc/alias.c b/gcc/alias.c
index efd89ce1679aff088dc3df20bac7b84d3727274f..e16e3501522e539f07759c4188aebb9f9ae859b6 100644 (file)
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -2046,6 +2046,18 @@ compare_base_decls (tree base1, tree base2)
   if (base1 == base2)
     return 1;
 
+  /* If we have two register decls with register specification we
+     cannot decide unless their assembler name is the same.  */
+  if (DECL_REGISTER (base1)
+      && DECL_REGISTER (base2)
+      && DECL_ASSEMBLER_NAME_SET_P (base1)
+      && DECL_ASSEMBLER_NAME_SET_P (base2))
+    {
+      if (DECL_ASSEMBLER_NAME (base1) == DECL_ASSEMBLER_NAME (base2))
+       return 1;
+      return -1;
+    }
+
   /* Declarations of non-automatic variables may have aliases.  All other
      decls are unique.  */
   if (!decl_in_symtab_p (base1)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fd6b9fa902bb420ddb541553e09688959f16528d..576838e0d4185b4b6bded2f8734bc189c0a21ca4 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-04-25  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/80492
+       * gcc.dg/pr80492.c: New testcase.
+
 2017-04-25  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
 
        * gcc.dg/attr-alloc_size-10.c: Ignore overflow warnings

diff --git a/gcc/testsuite/gcc.dg/pr80492.c b/gcc/testsuite/gcc.dg/pr80492.c
new file mode 100644 (file)
index 0000000..1721b2d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr80492.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-w -O2 -fdump-tree-optimized" } */
+
+static __inline__ __attribute__((__always_inline__))
+void syscall_7 (int val)
+{
+  register int reg __asm ("4") = val;
+  __asm __volatile__ ("/* Some Code %0 */" :: "r" (reg));
+}
+
+void do_syscalls (void)
+{
+  for (int s = 0; s < 2; s++)
+    {
+      syscall_7 (0);
+      syscall_7 (1);
+    }
+}
+
+/* { dg-final { scan-tree-dump-times "reg = " 4 "optimized" } } */

diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 3f0c650475d16305f72597e5198138a569b9e657..0dcb273e5c2e236f29a992530d4dafd9cda34958 100644 (file)
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -1096,13 +1096,16 @@ decl_refs_may_alias_p (tree ref1, tree base1,
 {
   gcc_checking_assert (DECL_P (base1) && DECL_P (base2));
 
+  int cmp = compare_base_decls (base1, base2);
+
   /* If both references are based on different variables, they cannot alias.  */
-  if (compare_base_decls (base1, base2) == 0)
+  if (cmp == 0)
     return false;
 
   /* If both references are based on the same variable, they cannot alias if
      the accesses do not overlap.  */
-  if (!ranges_overlap_p (offset1, max_size1, offset2, max_size2))
+  if (cmp == 1
+      && !ranges_overlap_p (offset1, max_size1, offset2, max_size2))
     return false;
 
   /* For components with variable position, the above test isn't sufficient,