Add method for replacing instructions to LibCallSimplifier

In some cases the library call simplifier may need to replace instructions
other than the library call being simplified.  In those cases it may be
necessary for clients of the simplifier to override how the replacements
are actually done.  As such, a new overrideable method for replacing
instructions was added to LibCallSimplifier.

A new subclass of LibCallSimplifier is also defined which overrides
the instruction replacement method.  This is because the instruction
combiner defines its own replacement method which updates the worklist
when instructions are replaced.

llvm-svn: 167681

1 files changed, 19 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index ccf75bca2b9..9a46f25e66f 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2367,6 +2367,24 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
   return MadeIRChange;
 }
 
+namespace {
+class InstCombinerLibCallSimplifier : public LibCallSimplifier {
+  InstCombiner *IC;
+public:
+  InstCombinerLibCallSimplifier(const DataLayout *TD,
+                                const TargetLibraryInfo *TLI,
+                                InstCombiner *IC)
+    : LibCallSimplifier(TD, TLI) {
+    this->IC = IC;
+  }
+
+  /// replaceAllUsesWith - override so that instruction replacement
+  /// can be defined in terms of the instruction combiner framework.
+  virtual void replaceAllUsesWith(Instruction *I, Value *With) const {
+    IC->ReplaceInstUsesWith(*I, With);
+  }
+};
+}
 
 bool InstCombiner::runOnFunction(Function &F) {
   TD = getAnalysisIfAvailable<DataLayout>();
@@ -2379,7 +2397,7 @@ bool InstCombiner::runOnFunction(Function &F) {
                InstCombineIRInserter(Worklist));
   Builder = &TheBuilder;
 
-  LibCallSimplifier TheSimplifier(TD, TLI);
+  InstCombinerLibCallSimplifier TheSimplifier(TD, TLI, this);
   Simplifier = &TheSimplifier;
 
   bool EverMadeChange = false;