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Revert the backend fatal error from r196939

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The combination of inline asm, stack realignment, and dynamic allocas
turns out to be too common to reject out of hand.

ASan inserts empy inline asm fragments and uses aligned allocas.
Compiling any trivial function containing a dynamic alloca with ASan is
enough to trigger the check.

XFAIL the test cases that would be miscompiled and add one that uses the
relevant functionality.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196986 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2013-12-10 23:23:52 +00:00
parent 9e9622d63e
commit 4d5bee428f
4 changed files with 35 additions and 11 deletions
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6
lib/Target/X86/X86RegisterInfo.cpp
View File

@ -347,12 +347,6 @@ BitVector X86RegisterInfo::getReservedRegs(const MachineFunction &MF) const {
"Stack realignment in presence of dynamic allocas is not supported with"
"this calling convention.");
// FIXME: Do a proper analysis of the inline asm to see if it actually
// conflicts with the base register we chose.
if (MF.hasInlineAsm())
report_fatal_error("Stack realignment in presence of dynamic stack "
"adjustments is not supported with inline assembly.");
for (MCSubRegIterator I(getBaseRegister(), this, /*IncludeSelf=*/true);
I.isValid(); ++I)
Reserved.set(*I);

6
test/CodeGen/X86/inline-asm-stack-realign.ll
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@ -1,8 +1,8 @@
; RUN: not llc -mtriple=i686-pc-win32 < %s 2>&1 | FileCheck %s
; We don't currently support realigning the stack and adjusting the stack
; pointer in inline asm. This commonly happens in MS inline assembly using
; push and pop.
; FIXME: This is miscompiled due to our unconditional use of ESI as the base
; pointer.
; XFAIL:
; CHECK: Stack realignment in presence of dynamic stack adjustments is not supported with inline assembly

5
test/CodeGen/X86/inline-asm-stack-realign2.ll
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@ -1,7 +1,8 @@
; RUN: not llc -mtriple=i686-pc-win32 < %s 2>&1 | FileCheck %s
; We don't currently support realigning the stack and adjusting the stack
; pointer in inline asm. This can even happen in GNU asm.
; FIXME: This is miscompiled due to our unconditional use of ESI as the base
; pointer.
; XFAIL:
; CHECK: Stack realignment in presence of dynamic stack adjustments is not supported with inline assembly

29
test/CodeGen/X86/inline-asm-stack-realign3.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: llc -march=x86 < %s | FileCheck %s
declare void @bar(i32* %junk)
define i32 @foo(i1 %cond) {
entry:
%r = alloca i32, align 128
store i32 -1, i32* %r, align 128
br i1 %cond, label %doit, label %skip
doit:
call void asm sideeffect "xor %ecx, %ecx\0A\09mov %ecx, $0", "=*m,~{ecx},~{flags}"(i32* %r)
%junk = alloca i32
call void @bar(i32* %junk)
br label %skip
skip:
%0 = load i32* %r, align 128
ret i32 %0
}
; CHECK-LABEL: foo:
; CHECK: pushl %ebp
; CHECK: andl $-128, %esp
; CHECK: xor %ecx, %ecx
; CHECK-NEXT: mov %ecx, (%esi)
; CHECK: movl (%esi), %eax
; CHECK: popl %ebp
; CHECK: ret