From f19497f7b0ce0dab5d35054e7ba652164b9ac123 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@sifive.com>
Date: Tue, 2 Aug 2022 21:19:30 -0700
Subject: [PATCH] [RISCV] Use InstVisitor in RISCVCodeGenPrepare. NFC

Makes it easy to add new instructions to look at without dispatching
manually.
---
 llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp | 62 +++++++++----------
 1 file changed, 28 insertions(+), 34 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp b/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp
index a19253da440e..5b51bca2f378 100644
--- a/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp
+++ b/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/CodeGen/TargetPassConfig.h"
+#include "llvm/IR/InstVisitor.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
@@ -31,7 +32,8 @@ STATISTIC(NumZExtToSExt, "Number of SExt instructions converted to ZExt");
 
 namespace {
 
-class RISCVCodeGenPrepare : public FunctionPass {
+class RISCVCodeGenPrepare : public FunctionPass,
+                            public InstVisitor<RISCVCodeGenPrepare, bool> {
   const DataLayout *DL;
   const RISCVSubtarget *ST;
 
@@ -49,35 +51,35 @@ public:
     AU.addRequired<TargetPassConfig>();
   }
 
-private:
-  bool optimizeZExt(ZExtInst *I);
-  bool optimizeAndExt(BinaryOperator *BO);
+  bool visitInstruction(Instruction &I) { return false; }
+  bool visitZExtInst(ZExtInst &I);
+  bool visitAnd(BinaryOperator &BO);
 };
 
 } // end anonymous namespace
 
-bool RISCVCodeGenPrepare::optimizeZExt(ZExtInst *ZExt) {
+bool RISCVCodeGenPrepare::visitZExtInst(ZExtInst &ZExt) {
   if (!ST->is64Bit())
     return false;
 
-  Value *Src = ZExt->getOperand(0);
+  Value *Src = ZExt.getOperand(0);
 
   // We only care about ZExt from i32 to i64.
-  if (!ZExt->getType()->isIntegerTy(64) || !Src->getType()->isIntegerTy(32))
+  if (!ZExt.getType()->isIntegerTy(64) || !Src->getType()->isIntegerTy(32))
     return false;
 
   // Look for an opportunity to replace (i64 (zext (i32 X))) with a sext if we
   // can determine that the sign bit of X is zero via a dominating condition.
   // This often occurs with widened induction variables.
   if (isImpliedByDomCondition(ICmpInst::ICMP_SGE, Src,
-                              Constant::getNullValue(Src->getType()), ZExt,
+                              Constant::getNullValue(Src->getType()), &ZExt,
                               *DL)) {
-    auto *SExt = new SExtInst(Src, ZExt->getType(), "", ZExt);
-    SExt->takeName(ZExt);
-    SExt->setDebugLoc(ZExt->getDebugLoc());
+    auto *SExt = new SExtInst(Src, ZExt.getType(), "", &ZExt);
+    SExt->takeName(&ZExt);
+    SExt->setDebugLoc(ZExt.getDebugLoc());
 
-    ZExt->replaceAllUsesWith(SExt);
-    ZExt->eraseFromParent();
+    ZExt.replaceAllUsesWith(SExt);
+    ZExt.eraseFromParent();
     ++NumZExtToSExt;
     return true;
   }
@@ -86,12 +88,12 @@ bool RISCVCodeGenPrepare::optimizeZExt(ZExtInst *ZExt) {
   // INT_MIN is poison, the sign bit is zero.
   using namespace PatternMatch;
   if (match(Src, m_Intrinsic<Intrinsic::abs>(m_Value(), m_One()))) {
-    auto *SExt = new SExtInst(Src, ZExt->getType(), "", ZExt);
-    SExt->takeName(ZExt);
-    SExt->setDebugLoc(ZExt->getDebugLoc());
+    auto *SExt = new SExtInst(Src, ZExt.getType(), "", &ZExt);
+    SExt->takeName(&ZExt);
+    SExt->setDebugLoc(ZExt.getDebugLoc());
 
-    ZExt->replaceAllUsesWith(SExt);
-    ZExt->eraseFromParent();
+    ZExt.replaceAllUsesWith(SExt);
+    ZExt.eraseFromParent();
     ++NumZExtToSExt;
     return true;
   }
@@ -103,18 +105,15 @@ bool RISCVCodeGenPrepare::optimizeZExt(ZExtInst *ZExt) {
 // but bits 63:32 are zero. If we can prove that bit 31 of X is 0, we can fill
 // the upper 32 bits with ones. A separate transform will turn (zext X) into
 // (sext X) for the same condition.
-bool RISCVCodeGenPrepare::optimizeAndExt(BinaryOperator *BO) {
+bool RISCVCodeGenPrepare::visitAnd(BinaryOperator &BO) {
   if (!ST->is64Bit())
     return false;
 
-  if (BO->getOpcode() != Instruction::And)
-    return false;
-
-  if (!BO->getType()->isIntegerTy(64))
+  if (!BO.getType()->isIntegerTy(64))
     return false;
 
   // Left hand side should be sext or zext.
-  Instruction *LHS = dyn_cast<Instruction>(BO->getOperand(0));
+  Instruction *LHS = dyn_cast<Instruction>(BO.getOperand(0));
   if (!LHS || (!isa<SExtInst>(LHS) && !isa<ZExtInst>(LHS)))
     return false;
 
@@ -123,7 +122,7 @@ bool RISCVCodeGenPrepare::optimizeAndExt(BinaryOperator *BO) {
     return false;
 
   // Right hand side should be a constant.
-  Value *RHS = BO->getOperand(1);
+  Value *RHS = BO.getOperand(1);
 
   auto *CI = dyn_cast<ConstantInt>(RHS);
   if (!CI)
@@ -145,7 +144,7 @@ bool RISCVCodeGenPrepare::optimizeAndExt(BinaryOperator *BO) {
 
   // Sign extend the constant and replace the And operand.
   C = SignExtend64<32>(C);
-  BO->setOperand(1, ConstantInt::get(LHS->getType(), C));
+  BO.setOperand(1, ConstantInt::get(LHS->getType(), C));
 
   return true;
 }
@@ -161,14 +160,9 @@ bool RISCVCodeGenPrepare::runOnFunction(Function &F) {
   DL = &F.getParent()->getDataLayout();
 
   bool MadeChange = false;
-  for (auto &BB : F) {
-    for (Instruction &I : llvm::make_early_inc_range(BB)) {
-      if (auto *ZExt = dyn_cast<ZExtInst>(&I))
-        MadeChange |= optimizeZExt(ZExt);
-      else if (I.getOpcode() == Instruction::And)
-        MadeChange |= optimizeAndExt(cast<BinaryOperator>(&I));
-    }
-  }
+  for (auto &BB : F)
+    for (Instruction &I : llvm::make_early_inc_range(BB))
+      MadeChange |= visit(I);
 
   return MadeChange;
 }
-- 
2.34.1