X86: Fix frameescape when not using an FP

We can't use TargetFrameLowering::getFrameIndexOffset directly, because
Win64 really wants the offset from the stack pointer at the end of the
prologue. Instead, use X86FrameLowering::getFrameIndexOffsetFromSP(),
which is a pretty close approximiation of that. It fails to handle cases
with interestingly large stack alignments, which is pretty uncommon on
Win64 and is TODO.

llvm-svn: 233137

lib/CodeGen/MachineFunction.cpp

@@ -584,14 +584,6 @@ int MachineFrameInfo::CreateFixedSpillStackObject(uint64_t Size,
   return -++NumFixedObjects;
 }
 
-int MachineFrameInfo::CreateFrameAllocation(uint64_t Size) {
-  // Force the use of a frame pointer. The intention is that this intrinsic be
-  // used in conjunction with unwind mechanisms that leak the frame pointer.
-  setFrameAddressIsTaken(true);
-  Size = RoundUpToAlignment(Size, StackAlignment);
-  return CreateStackObject(Size, StackAlignment, false);
-}
-
 BitVector
 MachineFrameInfo::getPristineRegs(const MachineBasicBlock *MBB) const {
   assert(MBB && "MBB must be valid");

lib/Target/X86/X86RegisterInfo.cpp

@@ -14,6 +14,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "X86RegisterInfo.h"
+#include "X86FrameLowering.h"
 #include "X86InstrBuilder.h"
 #include "X86MachineFunctionInfo.h"
 #include "X86Subtarget.h"
@@ -507,15 +508,14 @@ X86RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   // offset is from the SP at the end of the prologue, not the FP location. This
   // matches the behavior of llvm.frameaddress.
   if (Opc == TargetOpcode::FRAME_ALLOC) {
-    assert(TFI->hasFP(MF) && "frame alloc requires FP");
     MachineOperand &FI = MI.getOperand(FIOperandNum);
-    const MachineFrameInfo *MFI = MF.getFrameInfo();
-    int Offset = MFI->getObjectOffset(FrameIndex) - TFI->getOffsetOfLocalArea();
     bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
+    int Offset;
     if (IsWinEH)
-      Offset += MFI->getStackSize();
+      Offset = static_cast<const X86FrameLowering *>(TFI)
+                     ->getFrameIndexOffsetFromSP(MF, FrameIndex);
     else
-      Offset += SlotSize;
+      Offset = TFI->getFrameIndexOffset(MF, FrameIndex);
     FI.ChangeToImmediate(Offset);
     return;
   }

test/CodeGen/X86/frameescape.ll

@@ -1,4 +1,5 @@
-; RUN: llc -mtriple=x86_64-windows-msvc < %s | FileCheck %s
+; RUN: llc -mtriple=i686-windows-msvc < %s | FileCheck %s --check-prefix=X86
+; RUN: llc -mtriple=x86_64-windows-msvc < %s | FileCheck %s --check-prefix=X64
 
 declare void @llvm.frameescape(...)
 declare i8* @llvm.frameaddress(i32)
@@ -20,17 +21,34 @@ define void @print_framealloc_from_fp(i8* %fp) {
   ret void
 }
 
-; CHECK-LABEL: print_framealloc_from_fp:
-; CHECK: movq %rcx, %[[parent_fp:[a-z]+]]
-; CHECK: movl .Lalloc_func$frame_escape_0(%[[parent_fp]]), %edx
-; CHECK: leaq {{.*}}(%rip), %[[str:[a-z]+]]
-; CHECK: movq %[[str]], %rcx
-; CHECK: callq printf
-; CHECK: movl .Lalloc_func$frame_escape_1(%[[parent_fp]]), %edx
-; CHECK: movq %[[str]], %rcx
-; CHECK: callq printf
-; CHECK: movl    $42, .Lalloc_func$frame_escape_1(%[[parent_fp]])
-; CHECK: retq
+; X64-LABEL: print_framealloc_from_fp:
+; X64: movq %rcx, %[[parent_fp:[a-z]+]]
+; X64: movl .Lalloc_func$frame_escape_0(%[[parent_fp]]), %edx
+; X64: leaq {{.*}}(%rip), %[[str:[a-z]+]]
+; X64: movq %[[str]], %rcx
+; X64: callq printf
+; X64: movl .Lalloc_func$frame_escape_1(%[[parent_fp]]), %edx
+; X64: movq %[[str]], %rcx
+; X64: callq printf
+; X64: movl    $42, .Lalloc_func$frame_escape_1(%[[parent_fp]])
+; X64: retq
+
+; X86-LABEL: print_framealloc_from_fp:
+; X86: pushl   %esi
+; X86: subl    $8, %esp
+; X86: movl    16(%esp), %esi
+; X86: movl    _Lalloc_func$frame_escape_0(%esi), %eax
+; X86: movl    %eax, 4(%esp)
+; X86: movl    $_str, (%esp)
+; X86: calll   _printf
+; X86: movl    _Lalloc_func$frame_escape_1(%esi), %eax
+; X86: movl    %eax, 4(%esp)
+; X86: movl    $_str, (%esp)
+; X86: calll   _printf
+; X86: movl    $42, _Lalloc_func$frame_escape_1(%esi)
+; X86: addl    $8, %esp
+; X86: popl    %esi
+; X86: retl
 
 define void @alloc_func() {
   %a = alloca i32
@@ -43,21 +61,58 @@ define void @alloc_func() {
   ret void
 }
 
-; CHECK-LABEL: alloc_func:
-; CHECK: subq    $48, %rsp
-; CHECK: .seh_stackalloc 48
-; CHECK: leaq    48(%rsp), %rbp
-; CHECK: .seh_setframe 5, 48
-; CHECK: .Lalloc_func$frame_escape_0 = 44
-; CHECK: .Lalloc_func$frame_escape_1 = 40
-; CHECK: movl $42, -4(%rbp)
-; CHECK: movl $13, -8(%rbp)
-; CHECK: leaq    -48(%rbp), %rcx
-; CHECK: callq print_framealloc_from_fp
-; CHECK: retq
+; X64-LABEL: alloc_func:
+; X64: subq    $48, %rsp
+; X64: .seh_stackalloc 48
+; X64: leaq    48(%rsp), %rbp
+; X64: .seh_setframe 5, 48
+; X64: .Lalloc_func$frame_escape_0 = 44
+; X64: .Lalloc_func$frame_escape_1 = 40
+; X64: movl $42, -4(%rbp)
+; X64: movl $13, -8(%rbp)
+; X64: leaq    -48(%rbp), %rcx
+; X64: callq print_framealloc_from_fp
+; X64: retq
+
+; X86-LABEL: alloc_func:
+; X86: pushl   %ebp
+; X86: movl    %esp, %ebp
+; X86: subl    $12, %esp
+; X86: Lalloc_func$frame_escape_0 = -4
+; X86: Lalloc_func$frame_escape_1 = -8
+; X86: movl    $42, -4(%ebp)
+; X86: movl    $13, -8(%ebp)
+; X86: movl    %ebp, (%esp)
+; X86: calll   _print_framealloc_from_fp
+; X86: addl    $12, %esp
+; X86: popl    %ebp
+; X86: retl
 
 ; Helper to make this a complete program so it can be compiled and tested.
 define i32 @main() {
   call void @alloc_func()
   ret i32 0
 }
+
+define void @alloc_func_no_frameaddr() {
+  %a = alloca i32
+  %b = alloca i32
+  call void (...)* @llvm.frameescape(i32* %a, i32* %b)
+  store i32 42, i32* %a
+  store i32 13, i32* %b
+  call void @print_framealloc_from_fp(i8* null)
+  ret void
+}
+
+; X64-LABEL: alloc_func_no_frameaddr:
+; X64: subq    $40, %rsp
+; X64: .seh_stackalloc 40
+; X64: .seh_endprologue
+; X64: .Lalloc_func_no_frameaddr$frame_escape_0 = 36
+; X64: .Lalloc_func_no_frameaddr$frame_escape_1 = 32
+; X64: movl $42, 36(%rsp)
+; X64: movl $13, 32(%rsp)
+; X64: xorl %ecx, %ecx
+; X64: callq print_framealloc_from_fp
+; X64: addq $40, %rsp
+; X64: retq