Revert "Reuse %rax after calling __chkstk on win64"
This reverts commit 01f8d579f7672872324208ac5bc4ac311e81b22e.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185781 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp
index 5db431b..9d66bfd 100644
--- a/lib/Target/X86/X86FrameLowering.cpp
+++ b/lib/Target/X86/X86FrameLowering.cpp
@@ -914,14 +914,11 @@
.addReg(X86::EFLAGS, RegState::Define | RegState::Implicit)
.setMIFlag(MachineInstr::FrameSetup);
- // MSVC x64's __chkstk does not adjust %rsp itself.
- // It also does not clobber %rax so we can reuse it when adjusting %rsp.
- if (isSPUpdateNeeded) {
- BuildMI(MBB, MBBI, DL, TII.get(X86::SUB64rr), StackPtr)
- .addReg(StackPtr)
- .addReg(X86::RAX)
- .setMIFlag(MachineInstr::FrameSetup);
- }
+ // MSVC x64's __chkstk needs to adjust %rsp.
+ // FIXME: %rax preserves the offset and should be available.
+ if (isSPUpdateNeeded)
+ emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, IsLP64,
+ UseLEA, TII, *RegInfo);
if (isEAXAlive) {
// Restore EAX
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index aaeaa5d..a6e894b 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -14434,11 +14434,12 @@
} else {
// __chkstk(MSVCRT): does not update stack pointer.
// Clobbers R10, R11 and EFLAGS.
+ // FIXME: RAX(allocated size) might be reused and not killed.
BuildMI(*BB, MI, DL, TII->get(X86::W64ALLOCA))
.addExternalSymbol("__chkstk")
.addReg(X86::RAX, RegState::Implicit)
.addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
- // RAX has the offset to be subtracted from RSP.
+ // RAX has the offset to subtracted from RSP.
BuildMI(*BB, MI, DL, TII->get(X86::SUB64rr), X86::RSP)
.addReg(X86::RSP)
.addReg(X86::RAX);