[AMDGPU] Improve StructurizeCFG pass performance by using SSAUpdaterBulk.

[vpykhtin]

This is a replacement PR for #130611 and PR llvm/llvm-project #135181 due to the parent branches change. No changes since.

[vpykhtin]

• [AMDGPU] Improve StructurizeCFG pass performance by using SSAUpdaterBulk. #150937 👈 (View in Graphite)
• [SSAUpdaterBulk] Add PHI simplification pass. #150936
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Valery Pykhtin (vpykhtin)

Changes

This is a replacement PR for #130611 and PR llvm/llvm-project #135181 due to the parent branches change. No changes since.

---

Full diff: https://github.com/llvm/llvm-project/pull/150937.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Scalar/StructurizeCFG.cpp (+15-10)

diff --git a/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp b/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
index 44e63a0583d1a..5d4f2d1a38407 100644
--- a/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
@@ -48,6 +48,7 @@
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
+#include "llvm/Transforms/Utils/SSAUpdaterBulk.h"
 #include <cassert>
 #include <utility>
 
@@ -319,7 +320,7 @@ class StructurizeCFG {
 
   void collectInfos();
 
-  void insertConditions(bool Loops);
+  void insertConditions(bool Loops, SSAUpdaterBulk &PhiInserter);
 
   void simplifyConditions();
 
@@ -668,10 +669,9 @@ void StructurizeCFG::collectInfos() {
 }
 
 /// Insert the missing branch conditions
-void StructurizeCFG::insertConditions(bool Loops) {
+void StructurizeCFG::insertConditions(bool Loops, SSAUpdaterBulk &PhiInserter) {
   BranchVector &Conds = Loops ? LoopConds : Conditions;
   Value *Default = Loops ? BoolTrue : BoolFalse;
-  SSAUpdater PhiInserter;
 
   for (BranchInst *Term : Conds) {
     assert(Term->isConditional());
@@ -680,8 +680,9 @@ void StructurizeCFG::insertConditions(bool Loops) {
     BasicBlock *SuccTrue = Term->getSuccessor(0);
     BasicBlock *SuccFalse = Term->getSuccessor(1);
 
-    PhiInserter.Initialize(Boolean, "");
-    PhiInserter.AddAvailableValue(Loops ? SuccFalse : Parent, Default);
+    unsigned Variable = PhiInserter.AddVariable("", Boolean);
+    PhiInserter.AddAvailableValue(Variable, Loops ? SuccFalse : Parent,
+                                  Default);
 
     BBPredicates &Preds = Loops ? LoopPreds[SuccFalse] : Predicates[SuccTrue];
 
@@ -694,7 +695,7 @@ void StructurizeCFG::insertConditions(bool Loops) {
         ParentInfo = PI;
         break;
       }
-      PhiInserter.AddAvailableValue(BB, PI.Pred);
+      PhiInserter.AddAvailableValue(Variable, BB, PI.Pred);
       Dominator.addAndRememberBlock(BB);
     }
 
@@ -703,9 +704,9 @@ void StructurizeCFG::insertConditions(bool Loops) {
       CondBranchWeights::setMetadata(*Term, ParentInfo.Weights);
     } else {
       if (!Dominator.resultIsRememberedBlock())
-        PhiInserter.AddAvailableValue(Dominator.result(), Default);
+        PhiInserter.AddAvailableValue(Variable, Dominator.result(), Default);
 
-      Term->setCondition(PhiInserter.GetValueInMiddleOfBlock(Parent));
+      PhiInserter.AddUse(Variable, &Term->getOperandUse(0));
     }
   }
 }
@@ -1410,8 +1411,12 @@ bool StructurizeCFG::run(Region *R, DominatorTree *DT,
   orderNodes();
   collectInfos();
   createFlow();
-  insertConditions(false);
-  insertConditions(true);
+
+  SSAUpdaterBulk PhiInserter;
+  insertConditions(false, PhiInserter);
+  insertConditions(true, PhiInserter);
+  PhiInserter.RewriteAndOptimizeAllUses(*DT);
+
   setPhiValues();
   simplifyHoistedPhis();
   simplifyConditions();

[shiltian]

Can you request an internal psdb full cycle to test this PR? StructurizeCFG seems very sensitive to changes and has caused a lot of downstream failures.

[vpykhtin]

Can you request an internal psdb full cycle to test this PR? StructurizeCFG seems very sensitive to changes and has caused a lot of downstream failures.

I did that before and it passed, but I'll double check, thanks!