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.

llvm-svn: 160248

1 files changed, 9 insertions, 14 deletions

diff --git a/llvm/test/CodeGen/X86/dynamic-allocas-VLAs.ll b/llvm/test/CodeGen/X86/dynamic-allocas-VLAs.ll
index c7970d491ee..54ae39b7112 100644
--- a/llvm/test/CodeGen/X86/dynamic-allocas-VLAs.ll
+++ b/llvm/test/CodeGen/X86/dynamic-allocas-VLAs.ll
@@ -85,20 +85,19 @@ entry:
 ; CHECK: _t4
 ; CHECK: pushq %rbp
 ; CHECK: movq %rsp, %rbp
-; CHECK: andq $-32, %rsp
 ; CHECK: pushq %r14
 ; CHECK: pushq %rbx
-; CHECK: subq $[[STACKADJ:[0-9]+]], %rsp
+; CHECK: andq $-32, %rsp
+; CHECK: subq ${{[0-9]+}}, %rsp
 ; CHECK: movq %rsp, %rbx
 ;
 ; CHECK: leaq {{[0-9]*}}(%rbx), %rdi
 ; CHECK: leaq {{[0-9]*}}(%rbx), %rdx
 ; CHECK: callq   _t4_helper
 ;
-; CHECK: addq $[[STACKADJ]], %rsp
+; CHECK: leaq -16(%rbp), %rsp
 ; CHECK: popq %rbx
 ; CHECK: popq %r14
-; CHECK: movq %rbp, %rsp
 ; CHECK: popq %rbp
 }
 
@@ -176,19 +175,17 @@ entry:
 ; CHECK: _t7
 ; CHECK:     pushq %rbp
 ; CHECK:     movq %rsp, %rbp
-; CHECK:     andq $-32, %rsp
 ; CHECK:     pushq %rbx
-; CHECK:     subq $[[ADJ:[0-9]+]], %rsp
+; CHECK:     andq $-32, %rsp
+; CHECK:     subq ${{[0-9]+}}, %rsp
 ; CHECK:     movq %rsp, %rbx
 
 ; Stack adjustment for byval
 ; CHECK:     subq {{.*}}, %rsp
 ; CHECK:     callq _bar
 ; CHECK-NOT: addq {{.*}}, %rsp
-; CHECK:     movq %rbx, %rsp
-; CHECK:     addq $[[ADJ]], %rsp
+; CHECK:     leaq -8(%rbp), %rsp
 ; CHECK:     popq %rbx
-; CHECK:     movq %rbp, %rsp
 ; CHECK:     popq %rbp
 }
 
@@ -229,14 +226,12 @@ entry:
 ; FORCE-ALIGN: _t9
 ; FORCE-ALIGN: pushq %rbp
 ; FORCE-ALIGN: movq %rsp, %rbp
-; FORCE-ALIGN: andq $-32, %rsp
 ; FORCE-ALIGN: pushq %rbx
-; FORCE-ALIGN: subq $24, %rsp
+; FORCE-ALIGN: andq $-32, %rsp
+; FORCE-ALIGN: subq $32, %rsp
 ; FORCE-ALIGN: movq %rsp, %rbx
 
-; FORCE-ALIGN: movq %rbx, %rsp
-; FORCE-ALIGN: addq $24, %rsp
+; FORCE-ALIGN: leaq -8(%rbp), %rsp
 ; FORCE-ALIGN: popq %rbx
-; FORCE-ALIGN: movq %rbp, %rsp
 ; FORCE-ALIGN: popq %rbp
 }