[X86] Restore X86 base pointer after call to llvm.eh.sjlj.setjmp

Commit on 

- This patch fixes the bug described in
  http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-May/062343.html

The fix allocates an extra slot just below the GPRs and stores the base pointer
there. This is done only for functions containing llvm.eh.sjlj.setjmp that also
need a base pointer. Because code containing llvm.eh.sjlj.setjmp saves all of
the callee-save GPRs in the prologue, the offset to the extra slot can be
computed before prologue generation runs.

Impact at run-time on affected functions is::

  - One extra store in the prologue, The store saves the base pointer.
  - One extra load after a llvm.eh.sjlj.setjmp. The load restores the base pointer.

Because the extra slot is just above a gap between frame-pointer-relative and
base-pointer-relative chunks of memory, there is no impact on other offset
calculations other than ensuring there is room for the extra slot.

http://reviews.llvm.org/D6388

Patch by Arch Robison <arch.robison@intel.com>

llvm-svn: 223329

1 files changed, 37 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/sjlj-baseptr.ll b/llvm/test/CodeGen/X86/sjlj-baseptr.ll
new file mode 100644
index 00000000000..e439ff4dbd2
--- /dev/null
+++ b/llvm/test/CodeGen/X86/sjlj-baseptr.ll
@@ -0,0 +1,37 @@
+; RUN: llc < %s -mtriple=i386-pc-linux -mcpu=corei7 -relocation-model=static | FileCheck --check-prefix=X86 %s
+; RUN: llc < %s -mtriple=x86_64-pc-linux -mcpu=corei7 -relocation-model=static | FileCheck --check-prefix=X64 %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+%Foo = type { [125 x i8] }
+
+declare i32 @llvm.eh.sjlj.setjmp(i8*) nounwind
+
+declare void @whatever(i64, %Foo*, i8**, i8*, i8*, i32)  #0
+
+attributes #0 = { nounwind uwtable "no-frame-pointer-elim"="true" }
+
+define i32 @test1(i64 %n, %Foo* byval nocapture readnone align 8 %f) #0 {
+entry:
+  %buf = alloca [5 x i8*], align 16
+  %p = alloca i8*, align 8
+  %q = alloca i8, align 64
+  %r = bitcast [5 x i8*]* %buf to i8*
+  %s = alloca i8, i64 %n, align 1
+  store i8* %s, i8** %p, align 8
+  %t = call i32 @llvm.eh.sjlj.setjmp(i8* %s)
+  call void @whatever(i64 %n, %Foo* %f, i8** %p, i8* %q, i8* %s, i32 %t) #1
+  ret i32 0
+; X86: movl    %esp, %esi
+; X86: movl    %esp, -16(%ebp)
+; X86: {{.LBB.*:}}
+; X86: movl    -16(%ebp), %esi
+; X86: {{.LBB.*:}}
+; X64: movq    %rsp, %rbx
+; X64: movq    %rsp, -48(%rbp)
+; X64: {{.LBB.*:}}
+; X64: movq    -48(%rbp), %rbx
+; X64: {{.LBB.*:}}
+}
+
+