From 9960d684bffb67992b6a4fb8606de21ceab21d74 Mon Sep 17 00:00:00 2001
From: Michael Kuperstein <michael.m.kuperstein@intel.com>
Date: Tue, 15 Dec 2015 18:50:32 +0000
Subject: [PATCH] [X86] MOVPC32r should only emit CFI adjustments when needed

We only want to emit CFI adjustments when actually using DWARF.
This fixes PR25828.

Differential Revision: http://reviews.llvm.org/D15522

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255664 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86MCInstLower.cpp |  9 +++++----
 test/CodeGen/X86/pr25828.ll       | 30 ++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 4 deletions(-)
 create mode 100644 test/CodeGen/X86/pr25828.ll

diff --git a/lib/Target/X86/X86MCInstLower.cpp b/lib/Target/X86/X86MCInstLower.cpp
index af386807cd7..d0c03d6ab7c 100644
--- a/lib/Target/X86/X86MCInstLower.cpp
+++ b/lib/Target/X86/X86MCInstLower.cpp
@@ -1145,11 +1145,12 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
     bool hasFP = FrameLowering->hasFP(*MF);
     
     // TODO: This is needed only if we require precise CFA.
-    bool NeedsDwarfCFI = 
-         (MMI->hasDebugInfo() || MF->getFunction()->needsUnwindTableEntry());
+    bool HasActiveDwarfFrame = OutStreamer->getNumFrameInfos() &&
+                               !OutStreamer->getDwarfFrameInfos().back().End;
+
     int stackGrowth = -RI->getSlotSize();
 
-    if (NeedsDwarfCFI && !hasFP) {
+    if (HasActiveDwarfFrame && !hasFP) {
       OutStreamer->EmitCFIAdjustCfaOffset(-stackGrowth);
     }
 
@@ -1160,7 +1161,7 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
     EmitAndCountInstruction(MCInstBuilder(X86::POP32r)
                             .addReg(MI->getOperand(0).getReg()));
 
-    if (NeedsDwarfCFI && !hasFP) {
+    if (HasActiveDwarfFrame && !hasFP) {
       OutStreamer->EmitCFIAdjustCfaOffset(stackGrowth);
     }
     return;
diff --git a/test/CodeGen/X86/pr25828.ll b/test/CodeGen/X86/pr25828.ll
new file mode 100644
index 00000000000..8fbabc7d0c6
--- /dev/null
+++ b/test/CodeGen/X86/pr25828.ll
@@ -0,0 +1,30 @@
+; RUN: llc < %s -mtriple=i686-pc-windows-msvc -relocation-model=pic | FileCheck %s
+; MOVPC32r should not generate CFI under windows
+
+; CHECK-LABEL: _foo:
+; CHECK-NOT: .cfi_adjust_cfa_offset
+define void @foo(i8) {
+entry-block:
+  switch i8 %0, label %bb2 [
+    i8 1, label %bb1
+    i8 2, label %bb2
+    i8 3, label %bb3
+    i8 4, label %bb4
+    i8 5, label %bb5
+  ]
+
+bb1:
+  ret void
+
+bb2:
+  ret void
+
+bb3:
+  ret void
+
+bb4:
+  ret void
+
+bb5:
+  ret void
+}
-- 
2.34.1