[NFC][EarlyIfConverter] Turn SSAIfConv into a local variable

[jmmartinez]

This change simplifies refactoring later.

For more context please refer to this draft.

[jmmartinez]

Hello @nvjle ,
I've started cherry-picking one-by-one the commits refactoring SSAIfConv from #106415 .

Could you give it a look ?

I've also tagged llvm::codegen and all the backends using this pass:

• PowerPC
• SystemZ
• AMDGPU
• X86
• AArch64
• Hexagon

[llvmbot]

@llvm/pr-subscribers-backend-systemz
@llvm/pr-subscribers-backend-amdgpu
@llvm/pr-subscribers-backend-aarch64
@llvm/pr-subscribers-backend-x86

@llvm/pr-subscribers-backend-powerpc

Author: Juan Manuel Martinez Caamaño (jmmartinez)

Changes

This change simplifies refactoring later.

For more context please refer to this draft.

---

Full diff: https://github.com/llvm/llvm-project/pull/107390.diff

1 Files Affected:

• (modified) llvm/lib/CodeGen/EarlyIfConversion.cpp (+20-21)

diff --git a/llvm/lib/CodeGen/EarlyIfConversion.cpp b/llvm/lib/CodeGen/EarlyIfConversion.cpp
index 0de8112fb72c89..ff2dae7a3b1784 100644
--- a/llvm/lib/CodeGen/EarlyIfConversion.cpp
+++ b/llvm/lib/CodeGen/EarlyIfConversion.cpp
@@ -163,8 +163,7 @@ class SSAIfConv {
   void rewritePHIOperands();
 
 public:
-  /// runOnMachineFunction - Initialize per-function data structures.
-  void runOnMachineFunction(MachineFunction &MF) {
+  SSAIfConv(MachineFunction &MF) {
     TII = MF.getSubtarget().getInstrInfo();
     TRI = MF.getSubtarget().getRegisterInfo();
     MRI = &MF.getRegInfo();
@@ -770,7 +769,6 @@ class EarlyIfConverter : public MachineFunctionPass {
   MachineLoopInfo *Loops = nullptr;
   MachineTraceMetrics *Traces = nullptr;
   MachineTraceMetrics::Ensemble *MinInstr = nullptr;
-  SSAIfConv IfConv;
 
 public:
   static char ID;
@@ -780,9 +778,9 @@ class EarlyIfConverter : public MachineFunctionPass {
   StringRef getPassName() const override { return "Early If-Conversion"; }
 
 private:
-  bool tryConvertIf(MachineBasicBlock*);
-  void invalidateTraces();
-  bool shouldConvertIf();
+  bool tryConvertIf(SSAIfConv &IfConv, MachineBasicBlock *);
+  void invalidateTraces(SSAIfConv &IfConv);
+  bool shouldConvertIf(SSAIfConv &IfConv);
 };
 } // end anonymous namespace
 
@@ -838,7 +836,7 @@ void updateLoops(MachineLoopInfo *Loops,
 } // namespace
 
 /// Invalidate MachineTraceMetrics before if-conversion.
-void EarlyIfConverter::invalidateTraces() {
+void EarlyIfConverter::invalidateTraces(SSAIfConv &IfConv) {
   Traces->verifyAnalysis();
   Traces->invalidate(IfConv.Head);
   Traces->invalidate(IfConv.Tail);
@@ -868,7 +866,7 @@ template <typename Remark> Remark &operator<<(Remark &R, Cycles C) {
 /// Apply cost model and heuristics to the if-conversion in IfConv.
 /// Return true if the conversion is a good idea.
 ///
-bool EarlyIfConverter::shouldConvertIf() {
+bool EarlyIfConverter::shouldConvertIf(SSAIfConv &IfConv) {
   // Stress testing mode disables all cost considerations.
   if (Stress)
     return true;
@@ -1061,11 +1059,11 @@ bool EarlyIfConverter::shouldConvertIf() {
 
 /// Attempt repeated if-conversion on MBB, return true if successful.
 ///
-bool EarlyIfConverter::tryConvertIf(MachineBasicBlock *MBB) {
+bool EarlyIfConverter::tryConvertIf(SSAIfConv &IfConv, MachineBasicBlock *MBB) {
   bool Changed = false;
-  while (IfConv.canConvertIf(MBB) && shouldConvertIf()) {
+  while (IfConv.canConvertIf(MBB) && shouldConvertIf(IfConv)) {
     // If-convert MBB and update analyses.
-    invalidateTraces();
+    invalidateTraces(IfConv);
     SmallVector<MachineBasicBlock *, 4> RemoveBlocks;
     IfConv.convertIf(RemoveBlocks);
     Changed = true;
@@ -1098,14 +1096,14 @@ bool EarlyIfConverter::runOnMachineFunction(MachineFunction &MF) {
   MinInstr = nullptr;
 
   bool Changed = false;
-  IfConv.runOnMachineFunction(MF);
+  SSAIfConv IfConv(MF);
 
   // Visit blocks in dominator tree post-order. The post-order enables nested
   // if-conversion in a single pass. The tryConvertIf() function may erase
   // blocks, but only blocks dominated by the head block. This makes it safe to
   // update the dominator tree while the post-order iterator is still active.
   for (auto *DomNode : post_order(DomTree))
-    if (tryConvertIf(DomNode->getBlock()))
+    if (tryConvertIf(IfConv, DomNode->getBlock()))
       Changed = true;
 
   return Changed;
@@ -1124,7 +1122,6 @@ class EarlyIfPredicator : public MachineFunctionPass {
   MachineDominatorTree *DomTree = nullptr;
   MachineBranchProbabilityInfo *MBPI = nullptr;
   MachineLoopInfo *Loops = nullptr;
-  SSAIfConv IfConv;
 
 public:
   static char ID;
@@ -1134,8 +1131,8 @@ class EarlyIfPredicator : public MachineFunctionPass {
   StringRef getPassName() const override { return "Early If-predicator"; }
 
 protected:
-  bool tryConvertIf(MachineBasicBlock *);
-  bool shouldConvertIf();
+  bool tryConvertIf(SSAIfConv &IfConv, MachineBasicBlock *);
+  bool shouldConvertIf(SSAIfConv &IfConv);
 };
 } // end anonymous namespace
 
@@ -1162,7 +1159,7 @@ void EarlyIfPredicator::getAnalysisUsage(AnalysisUsage &AU) const {
 }
 
 /// Apply the target heuristic to decide if the transformation is profitable.
-bool EarlyIfPredicator::shouldConvertIf() {
+bool EarlyIfPredicator::shouldConvertIf(SSAIfConv &IfConv) {
   auto TrueProbability = MBPI->getEdgeProbability(IfConv.Head, IfConv.TBB);
   if (IfConv.isTriangle()) {
     MachineBasicBlock &IfBlock =
@@ -1202,9 +1199,11 @@ bool EarlyIfPredicator::shouldConvertIf() {
 
 /// Attempt repeated if-conversion on MBB, return true if successful.
 ///
-bool EarlyIfPredicator::tryConvertIf(MachineBasicBlock *MBB) {
+bool EarlyIfPredicator::tryConvertIf(SSAIfConv &IfConv,
+                                     MachineBasicBlock *MBB) {
   bool Changed = false;
-  while (IfConv.canConvertIf(MBB, /*Predicate*/ true) && shouldConvertIf()) {
+  while (IfConv.canConvertIf(MBB, /*Predicate*/ true) &&
+         shouldConvertIf(IfConv)) {
     // If-convert MBB and update analyses.
     SmallVector<MachineBasicBlock *, 4> RemoveBlocks;
     IfConv.convertIf(RemoveBlocks, /*Predicate*/ true);
@@ -1233,14 +1232,14 @@ bool EarlyIfPredicator::runOnMachineFunction(MachineFunction &MF) {
   MBPI = &getAnalysis<MachineBranchProbabilityInfoWrapperPass>().getMBPI();
 
   bool Changed = false;
-  IfConv.runOnMachineFunction(MF);
+  SSAIfConv IfConv(MF);
 
   // Visit blocks in dominator tree post-order. The post-order enables nested
   // if-conversion in a single pass. The tryConvertIf() function may erase
   // blocks, but only blocks dominated by the head block. This makes it safe to
   // update the dominator tree while the post-order iterator is still active.
   for (auto *DomNode : post_order(DomTree))
-    if (tryConvertIf(DomNode->getBlock()))
+    if (tryConvertIf(IfConv, DomNode->getBlock()))
       Changed = true;
 
   return Changed;

[arsenm]

Didn't look at how this helps the use case, but seems fine