LLVM freeze instruction between mask and div 1/?

Author: alexbaden

third_party/intel/lib/LLVMIR/CMakeLists.txt

@@ -0,0 +1,6 @@
+add_triton_library(TritonIntelLLVMIR
+        LLVMIRFreezeMaskedDivRem.cpp
+
+        DEPENDS
+        LLVMIRIncGen
+        )

third_party/intel/lib/LLVMIR/LLVMIRFreezeMaskedDivRem.cpp

@@ -0,0 +1,63 @@
+#include "LLVMPasses.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/Dominators.h"
+
+using namespace llvm;
+
+static bool processPhiNode(PHINode *phiNode, BasicBlock& BB) {
+      llvm::errs() << "YOLO: " << *phiNode << "\n";
+
+  const auto phiHasNullValue = any_of(phiNode->incoming_values(), [](Use& U) {
+    if (Constant *C = dyn_cast<Constant>(&U)) {
+      return C->isNullValue();
+    }
+    return false; 
+  });
+
+  if (phiHasNullValue) {
+        auto FindUse = llvm::find_if(phiNode->users(), [](auto *U) {
+          auto *Use = cast<Instruction>(U);
+          llvm::errs() << "User: " << *Use << "\n";
+          return (Use->getOpcode() == Instruction::SDiv);
+        });
+        if (FindUse == phiNode->user_end()) {
+          llvm::errs() << "no div :(\n";
+          return false; 
+        }
+        auto *Use = cast<Instruction>(*FindUse);
+        assert()
+        llvm::errs() << "Got our user! " << *Use << "\n";
+
+        // insert freeze between phi and sdiv 
+        // 
+  }
+  return false; 
+}
+
+static bool runOnFunction(Function& F, const TargetTransformInfo &TTI,
+                           const DominatorTree &DT) {
+    bool Changed = false;
+
+    SmallVector<PHINode *> PhiNodes;
+    for (BasicBlock &BB : F) {
+    for (Instruction &inst : BB) {
+      if (PHINode *phiNode = dyn_cast<PHINode>(&inst)) {
+        Changed |= processPhiNode(phiNode, BB);
+        continue;
+      }
+      break;
+    }
+  }
+
+    return Changed;
+}
+
+ PreservedAnalyses FreezeMaskedDivRemPass::run(Function &F, FunctionAnalysisManager &FAM) {
+    TargetTransformInfo &TTI = FAM.getResult<TargetIRAnalysis>(F);
+    DominatorTree &DT = FAM.getResult<DominatorTreeAnalysis>(F);
+    const auto b = runOnFunction(F, TTI, DT);
+
+    return b ? PreservedAnalyses::none() : PreservedAnalyses::all();
+}

third_party/intel/lib/LLVMIR/LLVMPasses.h

@@ -0,0 +1,11 @@
+#include "llvm/IR/PassManager.h"
+#include "llvm/Pass.h"
+
+namespace llvm {
+
+struct FreezeMaskedDivRemPass : PassInfoMixin<FreezeMaskedDivRemPass> {
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+  static StringRef name() { return "FreezeMaskedDivRemPass"; }
+};
+
+}