Re: [PATCH, PR66444] Handle -fipa-ra in reload_combine

[Tom de Vries <Tom_deVries at mentor dot com>]

On 08/06/15 17:31, Jakub Jelinek wrote:
> On Mon, Jun 08, 2015 at 02:04:12PM +0200, Tom de Vries wrote:
> > this patch fixes PR66444, a problem with -fipa-ra in reload_combine.
> >
> > The problem is that for the test-case, reload_combine combines these two
> > insns:
>
> Please work out with Vlad whether reload_cse_move2add doesn't need similar
> fix (and check other spots too).
>
> > 2015-06-08  Tom de Vries  <tom@codesourcery.com>
> >
> > 	PR rtl-optimization/66444
> > 	* postreload.c (reload_combine): Use get_call_reg_set_usage instead of
> > 	call_used_regs.
>
> LGTM.
>
> > 	* gcc.dg/pr66444.c: New test.
>
> > +int __attribute__((noinline, noclone))
> > +baz (void)
> > +{
> > +  struct S *x = (struct S *) 0xe0000000U;
>
> I'm still afraid this will not really work on s390-linux (which has only
> 31-bit pointers) and will not work on 16-bit int targets either
> (some have say 24-bit pointers etc., not really familiar with the embedded
> world).
> So, I'd suggest use a macro for the address, so you don't need to duplicate
> it,

Used a macro CONST_PTR.

> and define it to say ((struct S *) 0x8000UL), if it reproduces
> even with that change without your reload_combine fix.

Unfortunately, it didn't. So I used __SIZEOF_POINTER__ to produce a 
valid constant pointer for the 16-31 bit pointer-size cases, while still 
triggering the original problem for x86_64 -m64 case using a larger pointer.

Furthermore, I used __SIZEOF_POINTER__ to ensured a valid pointer 
constant suffix.

> Ok for trunk and 5.2 with that change.

Committed to trunk and backported gcc-5-branch as attached.

Thanks,
- Tom

Handle -fipa-ra in reload_combine

2015-06-08  Tom de Vries  <tom@codesourcery.com>

	PR rtl-optimization/66444
	* postreload.c (reload_combine): Use get_call_reg_set_usage instead of
	call_used_regs.

	* gcc.dg/pr66444.c: New test.
---
 gcc/postreload.c               |  5 ++-
 gcc/testsuite/gcc.dg/pr66444.c | 79 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr66444.c

diff --git a/gcc/postreload.c b/gcc/postreload.c
index 7ecca15..1cc7b14 100644
--- a/gcc/postreload.c
+++ b/gcc/postreload.c
@@ -1352,9 +1352,12 @@ reload_combine (void)
       if (CALL_P (insn))
 	{
 	  rtx link;
+	  HARD_REG_SET used_regs;
+
+	  get_call_reg_set_usage (insn, &used_regs, call_used_reg_set);
 
 	  for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
-	    if (call_used_regs[r])
+	    if (TEST_HARD_REG_BIT (used_regs, r))
 	      {
 		reg_state[r].use_index = RELOAD_COMBINE_MAX_USES;
 		reg_state[r].store_ruid = reload_combine_ruid;
diff --git a/gcc/testsuite/gcc.dg/pr66444.c b/gcc/testsuite/gcc.dg/pr66444.c
new file mode 100644
index 0000000..3f92a5c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr66444.c
@@ -0,0 +1,79 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fipa-ra" } */
+
+extern void abort (void);
+
+#if (__SIZEOF_LONG_LONG__ == __SIZEOF_POINTER__)
+#define ADD_SUFFIX(a) a ## ULL
+#elif (__SIZEOF_LONG__ == __SIZEOF_POINTER__)
+#define ADD_SUFFIX(a) a ## UL
+#elif (__SIZEOF_INT__ == __SIZEOF_POINTER__)
+#define ADD_SUFFIX(a) a ## U
+#else
+#error Add target support here
+#endif
+
+#if __SIZEOF_POINTER__ <= 4
+/* Use a 16 bit pointer to have a valid pointer for 16-bit to 31-bit pointer
+   architectures.  Using sizeof, we cannot distinguish between 31-bit and 32-bit
+   pointer types, so we also handle the 32-bit pointer type case here.  */
+#define CONST_PTR ADD_SUFFIX (0x800)
+#else
+/* For x86_64 -m64, the problem reproduces with this 32-bit CONST_PTR, but not
+   with a 2-power below it.  */
+#define CONST_PTR ADD_SUFFIX (0x80000000)
+#endif
+
+int __attribute__((noinline, noclone))
+bar (void)
+{
+  return 1;
+}
+
+struct S
+{
+  unsigned long p, q, r;
+  void *v;
+};
+
+struct S *s1;
+struct S *s2;
+
+void __attribute__((noinline, noclone))
+fn2 (struct S *x)
+{
+  s2 = x;
+}
+
+__attribute__((noinline, noclone)) void *
+fn1 (struct S *x)
+{
+  /* Just a statement to make it a non-const function.  */
+  s1 = x;
+
+  return (void *)0;
+}
+
+int __attribute__((noinline, noclone))
+baz (void)
+{
+  struct S *x = (struct S *) CONST_PTR;
+
+  x += bar ();
+
+  fn1 (x);
+  fn2 (x);
+
+  return 0;
+}
+
+int
+main (void)
+{
+  baz ();
+
+  if (s2 != (((struct S *) CONST_PTR) + 1))
+    abort ();
+
+  return 0;
+}
-- 
1.9.1