[llvm] 6a008de - [Evaluator] Simplify handling of bitcasted calls

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2022-01-25T14:19:04+01:00
New Revision: 6a008de82a8965bd8aac4456e20a51a883e4126b

URL: https://github.com/llvm/llvm-project/commit/6a008de82a8965bd8aac4456e20a51a883e4126b
DIFF: https://github.com/llvm/llvm-project/commit/6a008de82a8965bd8aac4456e20a51a883e4126b.diff

LOG: [Evaluator] Simplify handling of bitcasted calls

When fetching the function, strip casts. When casting the result,
use the call result type. Don't actually inspect the bitcast.

Added: 
    

Modified: 
    llvm/include/llvm/Transforms/Utils/Evaluator.h
    llvm/lib/Transforms/Utils/Evaluator.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Transforms/Utils/Evaluator.h b/llvm/include/llvm/Transforms/Utils/Evaluator.h
index 9346212dd8889..99e826bf855f2 100644
--- a/llvm/include/llvm/Transforms/Utils/Evaluator.h
+++ b/llvm/include/llvm/Transforms/Utils/Evaluator.h
@@ -127,7 +127,7 @@ class Evaluator {
   }
 
   /// Casts call result to a type of bitcast call expression
-  Constant *castCallResultIfNeeded(Value *CallExpr, Constant *RV);
+  Constant *castCallResultIfNeeded(Type *ReturnType, Constant *RV);
 
   /// Given call site return callee and list of its formal arguments
   Function *getCalleeWithFormalArgs(CallBase &CB,

diff  --git a/llvm/lib/Transforms/Utils/Evaluator.cpp b/llvm/lib/Transforms/Utils/Evaluator.cpp
index 34f56b1a591d9..e73287c060ae4 100644
--- a/llvm/lib/Transforms/Utils/Evaluator.cpp
+++ b/llvm/lib/Transforms/Utils/Evaluator.cpp
@@ -245,17 +245,10 @@ static Function *getFunction(Constant *C) {
 Function *
 Evaluator::getCalleeWithFormalArgs(CallBase &CB,
                                    SmallVectorImpl<Constant *> &Formals) {
-  auto *V = CB.getCalledOperand();
+  auto *V = CB.getCalledOperand()->stripPointerCasts();
   if (auto *Fn = getFunction(getVal(V)))
     return getFormalParams(CB, Fn, Formals) ? Fn : nullptr;
-
-  auto *CE = dyn_cast<ConstantExpr>(V);
-  if (!CE || CE->getOpcode() != Instruction::BitCast ||
-      !getFormalParams(CB, getFunction(CE->getOperand(0)), Formals))
-    return nullptr;
-
-  return dyn_cast<Function>(
-      ConstantFoldLoadThroughBitcast(CE, CE->getOperand(0)->getType(), DL));
+  return nullptr;
 }
 
 bool Evaluator::getFormalParams(CallBase &CB, Function *F,
@@ -284,17 +277,13 @@ bool Evaluator::getFormalParams(CallBase &CB, Function *F,
 
 /// If call expression contains bitcast then we may need to cast
 /// evaluated return value to a type of the call expression.
-Constant *Evaluator::castCallResultIfNeeded(Value *CallExpr, Constant *RV) {
-  ConstantExpr *CE = dyn_cast<ConstantExpr>(CallExpr);
-  if (!RV || !CE || CE->getOpcode() != Instruction::BitCast)
+Constant *Evaluator::castCallResultIfNeeded(Type *ReturnType, Constant *RV) {
+  if (!RV || RV->getType() == ReturnType)
     return RV;
 
-  if (auto *FT =
-          dyn_cast<FunctionType>(CE->getType()->getPointerElementType())) {
-    RV = ConstantFoldLoadThroughBitcast(RV, FT->getReturnType(), DL);
-    if (!RV)
-      LLVM_DEBUG(dbgs() << "Failed to fold bitcast call expr\n");
-  }
+  RV = ConstantFoldLoadThroughBitcast(RV, ReturnType, DL);
+  if (!RV)
+    LLVM_DEBUG(dbgs() << "Failed to fold bitcast call expr\n");
   return RV;
 }
 
@@ -540,7 +529,7 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst, BasicBlock *&NextBB,
         if (Callee->isDeclaration()) {
           // If this is a function we can constant fold, do it.
           if (Constant *C = ConstantFoldCall(&CB, Callee, Formals, TLI)) {
-            InstResult = castCallResultIfNeeded(CB.getCalledOperand(), C);
+            InstResult = castCallResultIfNeeded(CB.getType(), C);
             if (!InstResult)
               return false;
             LLVM_DEBUG(dbgs() << "Constant folded function call. Result: "
@@ -564,7 +553,7 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst, BasicBlock *&NextBB,
             return false;
           }
           ValueStack.pop_back();
-          InstResult = castCallResultIfNeeded(CB.getCalledOperand(), RetVal);
+          InstResult = castCallResultIfNeeded(CB.getType(), RetVal);
           if (RetVal && !InstResult)
             return false;