From c98bd9f1a79adffe73acd337b6f7f9afa6bae078 Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Fri, 28 Dec 2012 11:30:55 +0000
Subject: [PATCH] Add entry points to instsimplify for simplifying calls. The
 entry points are nice and decomposed so that we can simplify synthesized
 calls as easily as actually call instructions. The internal utility still has
 the same behavior, it just now operates on a more generic interface so that I
 can extend the set of call simplifications that instsimplify knows about.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171189 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/InstructionSimplify.h | 20 ++++++++++++
 lib/Analysis/InstructionSimplify.cpp        | 35 ++++++++++++++++++---
 2 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/include/llvm/Analysis/InstructionSimplify.h b/include/llvm/Analysis/InstructionSimplify.h
index 721f0ddd2ea..dd643a04693 100644
--- a/include/llvm/Analysis/InstructionSimplify.h
+++ b/include/llvm/Analysis/InstructionSimplify.h
@@ -19,6 +19,8 @@
 #ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
 #define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
 
+#include "llvm/User.h"
+
 namespace llvm {
   template<typename T>
   class ArrayRef;
@@ -205,6 +207,24 @@ namespace llvm {
                        const TargetLibraryInfo *TLI = 0,
                        const DominatorTree *DT = 0);
 
+  /// \brief Given a function and iterators over arguments, see if we can fold
+  /// the result.
+  ///
+  /// If this call could not be simplified returns null.
+  Value *SimplifyCall(Value *F, User::op_iterator ArgBegin,
+                      User::op_iterator ArgEnd, const DataLayout *TD = 0,
+                      const TargetLibraryInfo *TLI = 0,
+                      const DominatorTree *DT = 0);
+
+  /// \brief Given a function and set of arguments, see if we can fold the
+  /// result.
+  ///
+  /// If this call could not be simplified returns null.
+  Value *SimplifyCall(Value *F, ArrayRef<Value *> Args,
+                      const DataLayout *TD = 0,
+                      const TargetLibraryInfo *TLI = 0,
+                      const DominatorTree *DT = 0);
+
   /// SimplifyInstruction - See if we can compute a simplified version of this
   /// instruction.  If not, this returns null.
   Value *SimplifyInstruction(Instruction *I, const DataLayout *TD = 0,
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 0b88f457627..f0696f070d8 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -2869,14 +2869,36 @@ Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
                            RecursionLimit);
 }
 
-static Value *SimplifyCallInst(CallInst *CI, const Query &) {
+template <typename IterTy>
+static Value *SimplifyCall(Value *F, IterTy ArgBegin, IterTy ArgEnd,
+                           const Query &Q, unsigned MaxRecurse) {
+  Type *Ty = F->getType();
+  if (PointerType *PTy = dyn_cast<PointerType>(Ty))
+    Ty = PTy->getElementType();
+  FunctionType *FTy = cast<FunctionType>(Ty);
+
   // call undef -> undef
-  if (isa<UndefValue>(CI->getCalledValue()))
-    return UndefValue::get(CI->getType());
+  if (isa<UndefValue>(F))
+    return UndefValue::get(FTy->getReturnType());
 
   return 0;
 }
 
+Value *llvm::SimplifyCall(Value *F, User::op_iterator ArgBegin,
+                          User::op_iterator ArgEnd, const DataLayout *TD,
+                          const TargetLibraryInfo *TLI,
+                          const DominatorTree *DT) {
+  return ::SimplifyCall(F, ArgBegin, ArgEnd, Query(TD, TLI, DT),
+                        RecursionLimit);
+}
+
+Value *llvm::SimplifyCall(Value *F, ArrayRef<Value *> Args,
+                          const DataLayout *TD, const TargetLibraryInfo *TLI,
+                          const DominatorTree *DT) {
+  return ::SimplifyCall(F, Args.begin(), Args.end(), Query(TD, TLI, DT),
+                        RecursionLimit);
+}
+
 /// SimplifyInstruction - See if we can compute a simplified version of this
 /// instruction.  If not, this returns null.
 Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *TD,
@@ -2985,9 +3007,12 @@ Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *TD,
   case Instruction::PHI:
     Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT));
     break;
-  case Instruction::Call:
-    Result = SimplifyCallInst(cast<CallInst>(I), Query (TD, TLI, DT));
+  case Instruction::Call: {
+    CallSite CS(cast<CallInst>(I));
+    Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(),
+                          TD, TLI, DT);
     break;
+  }
   case Instruction::Trunc:
     Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, DT);
     break;
-- 
2.34.1