[PATCH] D98611: [InstSimplify] Restrict a GEP transform to avoid provenance changes

[Simonas Kazlauskas via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG6513995be37b: [InstSimplify] Restrict a GEP transform to avoid provenance changes (authored by nagisa).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98611/new/

https://reviews.llvm.org/D98611

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/test/Transforms/InstSimplify/gep.ll


Index: llvm/test/Transforms/InstSimplify/gep.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/gep.ll
+++ llvm/test/Transforms/InstSimplify/gep.ll
@@ -7,7 +7,12 @@
 
 define %struct.A* @test1(%struct.A* %b, %struct.A* %e) {
 ; CHECK-LABEL: @test1(
-; CHECK-NEXT:    ret %struct.A* [[E:%.*]]
+; CHECK-NEXT:    [[E_PTR:%.*]] = ptrtoint %struct.A* [[E:%.*]] to i64
+; CHECK-NEXT:    [[B_PTR:%.*]] = ptrtoint %struct.A* [[B:%.*]] to i64
+; CHECK-NEXT:    [[SUB:%.*]] = sub i64 [[E_PTR]], [[B_PTR]]
+; CHECK-NEXT:    [[SDIV:%.*]] = sdiv exact i64 [[SUB]], 7
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds [[STRUCT_A:%.*]], %struct.A* [[B]], i64 [[SDIV]]
+; CHECK-NEXT:    ret %struct.A* [[GEP]]
 ;
   %e_ptr = ptrtoint %struct.A* %e to i64
   %b_ptr = ptrtoint %struct.A* %b to i64
@@ -19,7 +24,11 @@
 
 define i8* @test2(i8* %b, i8* %e) {
 ; CHECK-LABEL: @test2(
-; CHECK-NEXT:    ret i8* [[E:%.*]]
+; CHECK-NEXT:    [[E_PTR:%.*]] = ptrtoint i8* [[E:%.*]] to i64
+; CHECK-NEXT:    [[B_PTR:%.*]] = ptrtoint i8* [[B:%.*]] to i64
+; CHECK-NEXT:    [[SUB:%.*]] = sub i64 [[E_PTR]], [[B_PTR]]
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds i8, i8* [[B]], i64 [[SUB]]
+; CHECK-NEXT:    ret i8* [[GEP]]
 ;
   %e_ptr = ptrtoint i8* %e to i64
   %b_ptr = ptrtoint i8* %b to i64
@@ -30,7 +39,12 @@
 
 define i64* @test3(i64* %b, i64* %e) {
 ; CHECK-LABEL: @test3(
-; CHECK-NEXT:    ret i64* [[E:%.*]]
+; CHECK-NEXT:    [[E_PTR:%.*]] = ptrtoint i64* [[E:%.*]] to i64
+; CHECK-NEXT:    [[B_PTR:%.*]] = ptrtoint i64* [[B:%.*]] to i64
+; CHECK-NEXT:    [[SUB:%.*]] = sub i64 [[E_PTR]], [[B_PTR]]
+; CHECK-NEXT:    [[ASHR:%.*]] = ashr exact i64 [[SUB]], 3
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds i64, i64* [[B]], i64 [[ASHR]]
+; CHECK-NEXT:    ret i64* [[GEP]]
 ;
   %e_ptr = ptrtoint i64* %e to i64
   %b_ptr = ptrtoint i64* %b to i64
Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4349,11 +4349,9 @@
       // doesn't truncate the pointers.
       if (Ops[1]->getType()->getScalarSizeInBits() ==
           Q.DL.getPointerSizeInBits(AS)) {
-        auto CanSimplify = [GEPTy, &P]() -> bool {
-          // FIXME: The following transforms are only legal if P and V have the
-          // same provenance (PR44403). Check whether getUnderlyingObject() is
-          // the same?
-          return P->getType() == GEPTy;
+        auto CanSimplify = [GEPTy, &P, V = Ops[0]]() -> bool {
+          return P->getType() == GEPTy &&
+                 getUnderlyingObject(P) == getUnderlyingObject(V);
         };
         // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
         if (TyAllocSize == 1 &&


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