[framelowering] Skip dbg values when getting next/previous instruction.

Summary:
In mergeSPUpdates, debug values need to be ignored when getting the
previous element, otherwise debug data could have an impact on codegen.

In eliminateCallFramePseudoInstr, debug values after the erased element
could have an impact on codegen and should be skipped.

Closes PR31319 (https://llvm.org/bugs/show_bug.cgi?id=31319)

Reviewers: mkuper, MatzeB, aprantl

Subscribers: gbedwell, llvm-commits

Differential Revision: https://reviews.llvm.org/D27688

llvm-svn: 290423

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 1deefe1231c..87355d46f9b 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -373,6 +373,10 @@ int X86FrameLowering::mergeSPUpdates(MachineBasicBlock &MBB,
   MachineBasicBlock::iterator PI = doMergeWithPrevious ? std::prev(MBBI) : MBBI;
   MachineBasicBlock::iterator NI = doMergeWithPrevious ? nullptr
                                                        : std::next(MBBI);
+  PI = skipDebugInstructionsBackward(PI, MBB.begin());
+  if (NI != nullptr)
+    NI = skipDebugInstructionsForward(NI, MBB.end());
+
   unsigned Opc = PI->getOpcode();
   int Offset = 0;
 
@@ -2586,6 +2590,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
   uint64_t Amount = !reserveCallFrame ? I->getOperand(0).getImm() : 0;
   uint64_t InternalAmt = (isDestroy || Amount) ? I->getOperand(1).getImm() : 0;
   I = MBB.erase(I);
+  I = skipDebugInstructionsForward(I, MBB.end());
 
   if (!reserveCallFrame) {
     // If the stack pointer can be changed after prologue, turn the