[X86] Ignore DBG instructions in X86CmovConversion optimization to resolve PR34565
Differential Revision: https://reviews.llvm.org/D38359
llvm-svn: 315851
diff --git a/llvm/lib/Target/X86/X86CmovConversion.cpp b/llvm/lib/Target/X86/X86CmovConversion.cpp
index fb76186..b2cd622 100644
--- a/llvm/lib/Target/X86/X86CmovConversion.cpp
+++ b/llvm/lib/Target/X86/X86CmovConversion.cpp
@@ -294,6 +294,9 @@
bool SkipGroup = false;
for (auto &I : *MBB) {
+ // Skip debug instructions.
+ if (I.isDebugValue())
+ continue;
X86::CondCode CC = X86::getCondFromCMovOpc(I.getOpcode());
// Check if we found a X86::CMOVrr instruction.
if (CC != X86::COND_INVALID && (IncludeLoads || !I.mayLoad())) {
@@ -431,6 +434,9 @@
// Clear physical registers Def map.
RegDefMaps[PhyRegType].clear();
for (MachineInstr &MI : *MBB) {
+ // Skip debug instructions.
+ if (MI.isDebugValue())
+ continue;
unsigned MIDepth = 0;
unsigned MIDepthOpt = 0;
bool IsCMOV = CmovInstructions.count(&MI);
@@ -589,11 +595,36 @@
return false;
}
+/// Given /p First CMOV instruction and /p Last CMOV instruction representing a
+/// group of CMOV instructions, which may contain debug instructions in between,
+/// move all debug instructions to after the last CMOV instruction, making the
+/// CMOV group consecutive.
+static void packCmovGroup(MachineInstr *First, MachineInstr *Last) {
+ assert(X86::getCondFromCMovOpc(Last->getOpcode()) != X86::COND_INVALID &&
+ "Last instruction in a CMOV group must be a CMOV instruction");
+
+ SmallVector<MachineInstr *, 2> DBGInstructions;
+ for (auto I = First->getIterator(), E = Last->getIterator(); I != E; I++) {
+ if (I->isDebugValue())
+ DBGInstructions.push_back(&*I);
+ }
+
+ // Splice the debug instruction after the cmov group.
+ MachineBasicBlock *MBB = First->getParent();
+ for (auto *MI : DBGInstructions)
+ MBB->insertAfter(Last, MI->removeFromParent());
+}
+
void X86CmovConverterPass::convertCmovInstsToBranches(
SmallVectorImpl<MachineInstr *> &Group) const {
assert(!Group.empty() && "No CMOV instructions to convert");
++NumOfOptimizedCmovGroups;
+ // If the CMOV group is not packed, e.g., there are debug instructions between
+ // first CMOV and last CMOV, then pack the group and make the CMOV instruction
+ // consecutive by moving the debug instructions to after the last CMOV.
+ packCmovGroup(Group.front(), Group.back());
+
// To convert a CMOVcc instruction, we actually have to insert the diamond
// control-flow pattern. The incoming instruction knows the destination vreg
// to set, the condition code register to branch on, the true/false values to