Allow replaceAndRecursivelySimplify to list unsimplified visitees.

This is part of D65280 and split it to avoid ABI changes on the 9.0
release branch.

llvm-svn: 370355

Author: jsonn

llvm/include/llvm/Analysis/InstructionSimplify.h

@@ -31,6 +31,7 @@
 #ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
 #define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
 
+#include "llvm/ADT/SetVector.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/User.h"
@@ -261,12 +262,14 @@ Value *SimplifyInstruction(Instruction *I, const SimplifyQuery &Q,
 /// This first performs a normal RAUW of I with SimpleV. It then recursively
 /// attempts to simplify those users updated by the operation. The 'I'
 /// instruction must not be equal to the simplified value 'SimpleV'.
+/// If UnsimplifiedUsers is provided, instructions that could not be simplified
+/// are added to it.
 ///
 /// The function returns true if any simplifications were performed.
-bool replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
-                                   const TargetLibraryInfo *TLI = nullptr,
-                                   const DominatorTree *DT = nullptr,
-                                   AssumptionCache *AC = nullptr);
+bool replaceAndRecursivelySimplify(
+    Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr,
+    const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr,
+    SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr);
 
 /// Recursively attempt to simplify an instruction.
 ///

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -5309,14 +5309,16 @@ Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ,
 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
 /// instructions to process and attempt to simplify it using
-/// InstructionSimplify.
+/// InstructionSimplify. Recursively visited users which could not be
+/// simplified themselves are to the optional UnsimplifiedUsers set for
+/// further processing by the caller.
 ///
 /// This routine returns 'true' only when *it* simplifies something. The passed
 /// in simplified value does not count toward this.
-static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
-                                              const TargetLibraryInfo *TLI,
-                                              const DominatorTree *DT,
-                                              AssumptionCache *AC) {
+static bool replaceAndRecursivelySimplifyImpl(
+    Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI,
+    const DominatorTree *DT, AssumptionCache *AC,
+    SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) {
   bool Simplified = false;
   SmallSetVector<Instruction *, 8> Worklist;
   const DataLayout &DL = I->getModule()->getDataLayout();
@@ -5346,8 +5348,11 @@ static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
 
     // See if this instruction simplifies.
     SimpleV = SimplifyInstruction(I, {DL, TLI, DT, AC});
-    if (!SimpleV)
+    if (!SimpleV) {
+      if (UnsimplifiedUsers)
+        UnsimplifiedUsers->insert(I);
       continue;
+    }
 
     Simplified = true;
 
@@ -5373,16 +5378,17 @@ bool llvm::recursivelySimplifyInstruction(Instruction *I,
                                           const TargetLibraryInfo *TLI,
                                           const DominatorTree *DT,
                                           AssumptionCache *AC) {
-  return replaceAndRecursivelySimplifyImpl(I, nullptr, TLI, DT, AC);
+  return replaceAndRecursivelySimplifyImpl(I, nullptr, TLI, DT, AC, nullptr);
 }
 
-bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
-                                         const TargetLibraryInfo *TLI,
-                                         const DominatorTree *DT,
-                                         AssumptionCache *AC) {
+bool llvm::replaceAndRecursivelySimplify(
+    Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI,
+    const DominatorTree *DT, AssumptionCache *AC,
+    SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) {
   assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
   assert(SimpleV && "Must provide a simplified value.");
-  return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC);
+  return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC,
+                                           UnsimplifiedUsers);
 }
 
 namespace llvm {