x86: Properly check register CFA offset
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Message ID CAMe9rOr=P30edOFJ_aEQHK5KQ=2JbhazwCE6kwx16ozaXiXOrQ@mail.gmail.com
State New
Headers show

Commit Message

H.J. Lu July 26, 2017, 7:15 p.m. UTC
On Wed, Jul 26, 2017 at 12:04 PM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Wed, Jul 26, 2017 at 6:14 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>>
>> X86 epilogue saves register at CFA offset.  Since its location on stack
>> is computed as CFA - its CFA_OFFSET, CFA_OFFSET points the end of the
>> saved register location on stack.  This patch updates sp_valid_at and
>> fp_valid_at to properly check register CFA offset.
>>
>> Tested on x86-64.  OK for trunk if there are no regressions on i686?
>>
>> Thanks.
>>
>> H.J.
>> --
>> gcc/
>>
>>         PR target/81563
>>         * config/i386/i386.c (sp_valid_at): Properly check CFA offset.
>>         (fp_valid_at): Likewise.
>>
>> gcc/testsuite/
>>
>>         PR target/81563
>>         * gcc.target/i386/pr81563.c: New test
>
> OK.
>

This is what I checked in with the updated commit log.

Thanks.

Patch
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From f7ccc9fc8419d08d8dbf9bd3ed3eec244196a6db Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 26 Jul 2017 09:06:22 -0700
Subject: [PATCH] x86: Properly check saved register CFA offset

X86 prologue saves register at CFA offset.  Since its location on stack
is computed as CFA - its CFA_OFFSET, CFA_OFFSET points the end of the
saved register area on stack.  This patch updates sp_valid_at and
fp_valid_at to properly check saved register CFA offset.

gcc/

	PR target/81563
	* config/i386/i386.c (sp_valid_at): Properly check CFA offset.
	(fp_valid_at): Likewise.

gcc/testsuite/

	PR target/81563
	* gcc.target/i386/pr81563.c: New test
---
 gcc/config/i386/i386.c                  | 10 ++++++----
 gcc/testsuite/gcc.target/i386/pr81563.c | 14 ++++++++++++++
 2 files changed, 20 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr81563.c

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 084b4a6a0db..f1486ff3750 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -13102,24 +13102,26 @@  choose_baseaddr_len (unsigned int regno, HOST_WIDE_INT offset)
   return len;
 }
 
-/* Determine if the stack pointer is valid for accessing the cfa_offset.  */
+/* Determine if the stack pointer is valid for accessing the cfa_offset.
+   The register is saved at CFA - CFA_OFFSET.  */
 
 static inline bool
 sp_valid_at (HOST_WIDE_INT cfa_offset)
 {
   const struct machine_frame_state &fs = cfun->machine->fs;
   return fs.sp_valid && !(fs.sp_realigned
-			  && cfa_offset < fs.sp_realigned_offset);
+			  && cfa_offset <= fs.sp_realigned_offset);
 }
 
-/* Determine if the frame pointer is valid for accessing the cfa_offset.  */
+/* Determine if the frame pointer is valid for accessing the cfa_offset.
+   The register is saved at CFA - CFA_OFFSET.  */
 
 static inline bool
 fp_valid_at (HOST_WIDE_INT cfa_offset)
 {
   const struct machine_frame_state &fs = cfun->machine->fs;
   return fs.fp_valid && !(fs.sp_valid && fs.sp_realigned
-			  && cfa_offset >= fs.sp_realigned_offset);
+			  && cfa_offset > fs.sp_realigned_offset);
 }
 
 /* Choose a base register based upon alignment requested, speed and/or
diff --git a/gcc/testsuite/gcc.target/i386/pr81563.c b/gcc/testsuite/gcc.target/i386/pr81563.c
new file mode 100644
index 00000000000..ebfd583daf5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr81563.c
@@ -0,0 +1,14 @@ 
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-O2 -maccumulate-outgoing-args -mincoming-stack-boundary=2 -mpreferred-stack-boundary=3 -mregparm=3 -mtune-ctrl=epilogue_using_move" } */
+
+extern void bar (long long int, int);
+
+long long int
+fn1 (long long int x)
+{
+  bar (x, 1);
+  return x;
+}
+
+/* { dg-final { scan-assembler-times "movl\[\\t \]*-8\\(%ebp\\),\[\\t \]*%esi" 1 } } */
+/* { dg-final { scan-assembler-times "movl\[\\t \]*-4\\(%ebp\\),\[\\t \]*%edi" 1 } } */
-- 
2.13.3