[InstCombine] Fix pointer replacement in foldSelectValueEquivalence

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -17,6 +17,7 @@
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/CmpInstAnalysis.h"
 #include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/Loads.h"
 #include "llvm/Analysis/OverflowInstAnalysis.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Analysis/VectorUtils.h"
@@ -1411,6 +1412,8 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
     // in the cmp and in f(Y).
     if (TrueVal == OldOp && (isa<Constant>(OldOp) || !isa<Constant>(NewOp)))
       return nullptr;
+    if (!canReplacePointersIfEqual(OldOp, NewOp, DL))
+      return nullptr;
 
     if (Value *V = simplifyWithOpReplaced(TrueVal, OldOp, NewOp, SQ,
                                           /* AllowRefinement=*/true)) {
@@ -1466,12 +1469,14 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
   // Example:
   // (X == 42) ? 43 : (X + 1) --> (X == 42) ? (X + 1) : (X + 1) --> X + 1
   SmallVector<Instruction *> DropFlags;
-  if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, SQ,
-                             /* AllowRefinement */ false,
-                             &DropFlags) == TrueVal ||
-      simplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, SQ,
-                             /* AllowRefinement */ false,
-                             &DropFlags) == TrueVal) {
+  if ((canReplacePointersIfEqual(CmpLHS, CmpRHS, DL) &&
+       simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, SQ,
+                              /* AllowRefinement */ false,
+                              &DropFlags) == TrueVal) ||
+      (canReplacePointersIfEqual(CmpRHS, CmpLHS, DL) &&
+       simplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, SQ,
+                              /* AllowRefinement */ false,
+                              &DropFlags) == TrueVal)) {
     for (Instruction *I : DropFlags) {
       I->dropPoisonGeneratingAnnotations();
       Worklist.add(I);

llvm/test/Transforms/InstCombine/select-gep.ll

@@ -290,7 +290,10 @@ define <2 x ptr> @test7(<2 x ptr> %p1, i64 %idx, <2 x i1> %cc) {
 define ptr @ptr_eq_replace_freeze1(ptr %p, ptr %q) {
 ; CHECK-LABEL: @ptr_eq_replace_freeze1(
 ; CHECK-NEXT:    [[Q_FR:%.*]] = freeze ptr [[Q:%.*]]
-; CHECK-NEXT:    ret ptr [[Q_FR]]
+; CHECK-NEXT:    [[Q_FR1:%.*]] = freeze ptr [[Q1:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[Q_FR]], [[Q_FR1]]
+; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP]], ptr [[Q_FR]], ptr [[Q_FR1]]
+; CHECK-NEXT:    ret ptr [[SELECT]]
 ;
   %p.fr = freeze ptr %p
   %q.fr = freeze ptr %q
@@ -302,7 +305,10 @@ define ptr @ptr_eq_replace_freeze1(ptr %p, ptr %q) {
 define ptr @ptr_eq_replace_freeze2(ptr %p, ptr %q) {
 ; CHECK-LABEL: @ptr_eq_replace_freeze2(
 ; CHECK-NEXT:    [[P_FR:%.*]] = freeze ptr [[P:%.*]]
-; CHECK-NEXT:    [[SELECT:%.*]] = getelementptr i8, ptr [[P_FR]], i64 16
+; CHECK-NEXT:    [[P_FR1:%.*]] = freeze ptr [[P1:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[P_FR1]], [[P_FR]]
+; CHECK-NEXT:    [[SELECT_V:%.*]] = select i1 [[CMP]], ptr [[P_FR1]], ptr [[P_FR]]
+; CHECK-NEXT:    [[SELECT:%.*]] = getelementptr i8, ptr [[SELECT_V]], i64 16
 ; CHECK-NEXT:    ret ptr [[SELECT]]
 ;
   %gep1 = getelementptr i32, ptr %p, i64 4