[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: aprantl, MatzeB, mkuper

Subscribers: gbedwell, llvm-commits

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

llvm-svn: 290955

1 files changed, 14 insertions, 8 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 1deefe1231c..cd690442bb9 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);
+  auto InsertPos = skipDebugInstructionsForward(I, MBB.end());
 
   if (!reserveCallFrame) {
     // If the stack pointer can be changed after prologue, turn the
@@ -2615,7 +2620,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
 
     if (HasDwarfEHHandlers && !isDestroy &&
         MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences())
-      BuildCFI(MBB, I, DL,
+      BuildCFI(MBB, InsertPos, DL,
                MCCFIInstruction::createGnuArgsSize(nullptr, Amount));
 
     if (Amount == 0)
@@ -2629,7 +2634,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
     // If this is a callee-pop calling convention, emit a CFA adjust for
     // the amount the callee popped.
     if (isDestroy && InternalAmt && DwarfCFI && !hasFP(MF))
-      BuildCFI(MBB, I, DL, 
+      BuildCFI(MBB, InsertPos, DL,
                MCCFIInstruction::createAdjustCfaOffset(nullptr, -InternalAmt));
 
     // Add Amount to SP to destroy a frame, or subtract to setup.
@@ -2640,13 +2645,13 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
       // Merge with any previous or following adjustment instruction. Note: the
       // instructions merged with here do not have CFI, so their stack
       // adjustments do not feed into CfaAdjustment.
-      StackAdjustment += mergeSPUpdates(MBB, I, true);
-      StackAdjustment += mergeSPUpdates(MBB, I, false);
+      StackAdjustment += mergeSPUpdates(MBB, InsertPos, true);
+      StackAdjustment += mergeSPUpdates(MBB, InsertPos, false);
 
       if (StackAdjustment) {
         if (!(Fn->optForMinSize() &&
-              adjustStackWithPops(MBB, I, DL, StackAdjustment)))
-          BuildStackAdjustment(MBB, I, DL, StackAdjustment,
+              adjustStackWithPops(MBB, InsertPos, DL, StackAdjustment)))
+          BuildStackAdjustment(MBB, InsertPos, DL, StackAdjustment,
                                /*InEpilogue=*/false);
       }
     }
@@ -2662,8 +2667,9 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
       // TODO: When not using precise CFA, we also need to adjust for the
       // InternalAmt here.
       if (CfaAdjustment) {
-        BuildCFI(MBB, I, DL, MCCFIInstruction::createAdjustCfaOffset(
-                                 nullptr, CfaAdjustment));
+        BuildCFI(MBB, InsertPos, DL,
+                 MCCFIInstruction::createAdjustCfaOffset(nullptr,
+                                                         CfaAdjustment));
       }
     }