This CL changes the function prologue and epilogue emitted on X86 when stack needs realignment.

It is intended to fix PR11468.

Old prologue and epilogue looked like this:
push %rbp
mov %rsp, %rbp
and $alignment, %rsp
push %r14
push %r15
...
pop %r15
pop %r14
mov %rbp, %rsp
pop %rbp

The problem was to reference the locations of callee-saved registers in exception handling:
locations of callee-saved had to be re-calculated regarding the stack alignment operation. It would
take some effort to implement this in LLVM, as currently MachineLocation can only have the form
"Register + Offset". Funciton prologue and epilogue are now changed to:

push %rbp
mov %rsp, %rbp
push %14
push %15
and $alignment, %rsp
...
lea -$size_of_saved_registers(%rbp), %rsp
pop %r15
pop %r14
pop %rbp

Reviewed by Chad Rosier.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160248 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 33 insertions, 0 deletions

diff --git a/test/CodeGen/X86/pr11468.ll b/test/CodeGen/X86/pr11468.ll
new file mode 100644
index 0000000000..f7e9adb4a2
--- /dev/null
+++ b/test/CodeGen/X86/pr11468.ll
@@ -0,0 +1,33 @@
+; RUN: llc < %s -force-align-stack -stack-alignment=32 -march=x86-64 -mattr=+avx -mtriple=i686-apple-darwin10 | FileCheck %s
+; PR11468
+
+define void @f(i64 %sz) uwtable {
+entry:
+  %a = alloca i32, align 32
+  store volatile i32 0, i32* %a, align 32
+  ; force to push r14 on stack
+  call void asm sideeffect "nop", "~{r14},~{dirflag},~{fpsr},~{flags}"() nounwind, !srcloc !0
+  ret void
+
+; CHECK: _f
+; CHECK: pushq %rbp
+; CHECK: .cfi_offset %rbp, -16
+; CHECK: movq %rsp, %rbp
+; CHECK: .cfi_def_cfa_register %rbp
+
+; We first push register on stack, and then realign it, so that
+; .cfi_offset value is correct
+; CHECK: pushq %r14
+; CHECK: andq $-32, %rsp
+; CHECK: .cfi_offset %r14, -24
+
+; Restore %rsp from %rbp and subtract the total size of saved regsiters.
+; CHECK: leaq -8(%rbp), %rsp
+
+; Pop saved registers.
+; CHECK: popq %r14
+; CHECK: popq %rbp
+}
+
+!0 = metadata !{i32 125}
+