Re: [Bug target/15551] [3.4/3.5? Regression] -mtune=pentium4 -O2with sjlj EH breaks stack probe worker on windows32 targets

[Kelley Cook <kcook at gcc dot gnu dot org>]

After deciphering the twisty passages.	I think this is a more correct fix.

The problem was not really a scheduling problem, it was that the Win32 
alloca routine was not marking that it affected memory, so gcc felt free 
to move stuff writing to the __alloca region before the call to __alloca.

I still need to regtest it (as that is REALLY slow on cygwin), but it 
survived a c,c++ bootstrap on i686-pc-cygwin and fixed the bug (writing 
to unalloca memory) as evidenced by below:

$ diff -u pm-gcc_35_orig.s pm-p4new.s
--- pm-gcc_35_orig.s	2004-06-01 14:25:47.170950500 -0400
+++ pm-p4new.s	2004-06-07 15:26:04.193903000 -0400
@@ -23,26 +23,26 @@
	movl	%esp, %ebp
	pushl	%edi
	pushl	%esi
-	movl	$___gxx_personality_sj0, -20052(%ebp)
-	movl	$LLSDA1422, -20048(%ebp)
	pushl	%ebx
-	movl	$L4, -20040(%ebp)
	call	__alloca
	movl	$16, %eax
	andl	$-16, %esp
	call	__alloca
	leal	-24(%ebp), %eax
+	movl	$___gxx_personality_sj0, -20052(%ebp)
	movl	%eax, -20044(%ebp)
	leal	-20076(%ebp), %eax
-	movl	%esp, -20036(%ebp)
+	movl	$LLSDA1422, -20048(%ebp)
	movl	%eax, (%esp)
+	movl	$L4, -20040(%ebp)
+	movl	%esp, -20036(%ebp)
	call	__Unwind_SjLj_Register
	call	___main
	movl	$256, (%esp)
	movl	$-1, -20072(%ebp)
	call	__Znwj
-	movl	%eax, -20080(%ebp)
	movl	$16, 8(%esp)
+	movl	%eax, -20080(%ebp)
	movl	$LC0, 4(%esp)
	movl	%eax, (%esp)
	movl	$1, -20072(%ebp)

This patch was against mainline, OK if it passed a complete regtest 
(which I should be able to check up on at work this morning)?

The patch also applies to 3.4 and passed an all languages bootstrap; 
I'll also regtest it there.

Mark, after a week on mainline, would this be OK for 3.4.1 assuming that 
it also passes?


Kelley Cook


2004-06-07  Kelley Cook  <kcook@gcc.gnu.org>

	* config/i386/i386.c (ix86_expand_prologue): Mark win32 allocate insn
	as prologue.
	* config/i386/i386.md (allocate_stack): Clobber alloca memory.
	(allocate_stack_worker_postreload): Likewise.
	(allocate_stack_worker_rex64): Likewise.
	(allocate_stack_worker_rex64_postreload): Likewise.
	(allocate_stack_worker_1): Likewise.

diff -upd ../../../../gcc-orig/gcc/config/i386/i386.c ./i386.c
--- ../../../../gcc-orig/gcc/config/i386/i386.c	2004-06-02 13:34:35.000000000 -0400
+++ ./i386.c	2004-06-07 15:38:53.587909000 -0400
@@ -5280,7 +5280,8 @@ ix86_expand_prologue (void)
 
       if (eax_live)
 	{
-	  emit_insn (gen_push (eax));
+	  insn = emit_insn (gen_push (eax));
+	  RTX_FRAME_RELATED_P (insn) = 1;
 	  allocate -= 4;
 	}
 
@@ -5293,7 +5294,8 @@ ix86_expand_prologue (void)
       if (eax_live)
 	{
 	  rtx t = plus_constant (stack_pointer_rtx, allocate);
-	  emit_move_insn (eax, gen_rtx_MEM (SImode, t));
+	  insn = emit_move_insn (eax, gen_rtx_MEM (SImode, t));
+	  RTX_FRAME_RELATED_P (insn) = 1;
 	}
     }
 
diff -upd ../../../../gcc-orig/gcc/config/i386/i386.md ./i386.md
--- ../../../../gcc-orig/gcc/config/i386/i386.md	2004-06-07 12:08:14.587894000 -0400
+++ ./i386.md	2004-06-07 15:38:02.133408000 -0400
@@ -18304,6 +18304,7 @@
   [(unspec:SI [(match_operand:SI 0 "register_operand" "a")] UNSPEC_STACK_PROBE)
    (set (reg:SI 7) (minus:SI (reg:SI 7) (match_dup 0)))
    (clobber (match_scratch:SI 1 "=0"))
+   (clobber (mem:BLK (scratch)))
    (clobber (reg:CC 17))]
   "!TARGET_64BIT && TARGET_STACK_PROBE"
   "call\t__alloca"
@@ -18315,6 +18316,7 @@
 			   UNSPEC_STACK_PROBE)
 	      (set (reg:SI 7) (minus:SI (reg:SI 7) (match_dup 0)))
 	      (clobber (match_dup 0))
+	      (clobber (mem:BLK (scratch)))
 	      (clobber (reg:CC 17))])]
   ""
   "")
@@ -18323,6 +18325,7 @@
   [(unspec:DI [(match_operand:DI 0 "register_operand" "a")] UNSPEC_STACK_PROBE)
    (set (reg:DI 7) (minus:DI (reg:DI 7) (match_dup 0)))
    (clobber (match_scratch:DI 1 "=0"))
+   (clobber (mem:BLK (scratch)))
    (clobber (reg:CC 17))]
   "TARGET_64BIT && TARGET_STACK_PROBE"
   "call\t__alloca"
@@ -18334,6 +18337,7 @@
 			   UNSPEC_STACK_PROBE)
 	      (set (reg:DI 7) (minus:DI (reg:DI 7) (match_dup 0)))
 	      (clobber (match_dup 0))
+	      (clobber (mem:BLK (scratch)))
 	      (clobber (reg:CC 17))])]
   ""
   "")
@@ -18345,6 +18349,7 @@
 	      (clobber (reg:CC 17))])
    (parallel [(set (reg:SI 7)
 		   (minus:SI (reg:SI 7) (match_dup 1)))
+	      (clobber (mem:BLK (scratch)))
 	      (clobber (reg:CC 17))])]
   "TARGET_STACK_PROBE"
 {