[InstSimplify] Fold ptrtoint(ptradd(P,X-ptrtoint(P))) to X#98649
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[InstSimplify] Fold ptrtoint(ptradd(P,X-ptrtoint(P))) to X#98649
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This is a special case of the general ptrtoint(gep) to add(ptrtoint) transform that is particularly profitable, as everything folds away. Proof: https://alive2.llvm.org/ce/z/fwv8_L Fixes llvm#86417.
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@llvm/pr-subscribers-llvm-analysis Author: Nikita Popov (nikic) ChangesThis is a special case of the general ptrtoint(gep) to add(ptrtoint) transform that is particularly profitable, as everything folds away. Proof: https://alive2.llvm.org/ce/z/fwv8_L Fixes #86417. 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 0917a362eccf5..242c200f7ef15 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5333,6 +5333,14 @@ static Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
if (Op->getType() == Ty)
return Op;
+ // ptrtoint (ptradd (Ptr, X - ptrtoint(Ptr))) -> X
+ Value *Ptr, *X;
+ if (CastOpc == Instruction::PtrToInt &&
+ match(Op, m_PtrAdd(m_Value(Ptr),
+ m_Sub(m_Value(X), m_PtrToInt(m_Deferred(Ptr))))) &&
+ X->getType() == Ty && Ty == Q.DL.getIndexType(Ptr->getType()))
+ return X;
+
return nullptr;
}
diff --git a/llvm/test/Transforms/InstSimplify/ptrtoint.ll b/llvm/test/Transforms/InstSimplify/ptrtoint.ll
index 55a5a0d452f10..734618713c342 100644
--- a/llvm/test/Transforms/InstSimplify/ptrtoint.ll
+++ b/llvm/test/Transforms/InstSimplify/ptrtoint.ll
@@ -4,11 +4,7 @@
define i64 @ptrtoint_gep_sub(ptr %ptr, i64 %end.addr) {
; CHECK-LABEL: define i64 @ptrtoint_gep_sub(
; CHECK-SAME: ptr [[PTR:%.*]], i64 [[END_ADDR:%.*]]) {
-; CHECK-NEXT: [[PTR_ADDR:%.*]] = ptrtoint ptr [[PTR]] to i64
-; CHECK-NEXT: [[SIZE:%.*]] = sub i64 [[END_ADDR]], [[PTR_ADDR]]
-; CHECK-NEXT: [[END:%.*]] = getelementptr i8, ptr [[PTR]], i64 [[SIZE]]
-; CHECK-NEXT: [[END_ADDR2:%.*]] = ptrtoint ptr [[END]] to i64
-; CHECK-NEXT: ret i64 [[END_ADDR2]]
+; CHECK-NEXT: ret i64 [[END_ADDR]]
;
%ptr.addr = ptrtoint ptr %ptr to i64
%size = sub i64 %end.addr, %ptr.addr
@@ -20,11 +16,7 @@ define i64 @ptrtoint_gep_sub(ptr %ptr, i64 %end.addr) {
define <2 x i64> @ptrtoint_gep_sub_vector(<2 x ptr> %ptr, <2 x i64> %end.addr) {
; CHECK-LABEL: define <2 x i64> @ptrtoint_gep_sub_vector(
; CHECK-SAME: <2 x ptr> [[PTR:%.*]], <2 x i64> [[END_ADDR:%.*]]) {
-; CHECK-NEXT: [[PTR_ADDR:%.*]] = ptrtoint <2 x ptr> [[PTR]] to <2 x i64>
-; CHECK-NEXT: [[SIZE:%.*]] = sub <2 x i64> [[END_ADDR]], [[PTR_ADDR]]
-; CHECK-NEXT: [[END:%.*]] = getelementptr i8, <2 x ptr> [[PTR]], <2 x i64> [[SIZE]]
-; CHECK-NEXT: [[END_ADDR2:%.*]] = ptrtoint <2 x ptr> [[END]] to <2 x i64>
-; CHECK-NEXT: ret <2 x i64> [[END_ADDR2]]
+; CHECK-NEXT: ret <2 x i64> [[END_ADDR]]
;
%ptr.addr = ptrtoint <2 x ptr> %ptr to <2 x i64>
%size = sub <2 x i64> %end.addr, %ptr.addr
|
Member
|
@llvm/pr-subscribers-llvm-transforms Author: Nikita Popov (nikic) ChangesThis is a special case of the general ptrtoint(gep) to add(ptrtoint) transform that is particularly profitable, as everything folds away. Proof: https://alive2.llvm.org/ce/z/fwv8_L Fixes #86417. 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 0917a362eccf5..242c200f7ef15 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5333,6 +5333,14 @@ static Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
if (Op->getType() == Ty)
return Op;
+ // ptrtoint (ptradd (Ptr, X - ptrtoint(Ptr))) -> X
+ Value *Ptr, *X;
+ if (CastOpc == Instruction::PtrToInt &&
+ match(Op, m_PtrAdd(m_Value(Ptr),
+ m_Sub(m_Value(X), m_PtrToInt(m_Deferred(Ptr))))) &&
+ X->getType() == Ty && Ty == Q.DL.getIndexType(Ptr->getType()))
+ return X;
+
return nullptr;
}
diff --git a/llvm/test/Transforms/InstSimplify/ptrtoint.ll b/llvm/test/Transforms/InstSimplify/ptrtoint.ll
index 55a5a0d452f10..734618713c342 100644
--- a/llvm/test/Transforms/InstSimplify/ptrtoint.ll
+++ b/llvm/test/Transforms/InstSimplify/ptrtoint.ll
@@ -4,11 +4,7 @@
define i64 @ptrtoint_gep_sub(ptr %ptr, i64 %end.addr) {
; CHECK-LABEL: define i64 @ptrtoint_gep_sub(
; CHECK-SAME: ptr [[PTR:%.*]], i64 [[END_ADDR:%.*]]) {
-; CHECK-NEXT: [[PTR_ADDR:%.*]] = ptrtoint ptr [[PTR]] to i64
-; CHECK-NEXT: [[SIZE:%.*]] = sub i64 [[END_ADDR]], [[PTR_ADDR]]
-; CHECK-NEXT: [[END:%.*]] = getelementptr i8, ptr [[PTR]], i64 [[SIZE]]
-; CHECK-NEXT: [[END_ADDR2:%.*]] = ptrtoint ptr [[END]] to i64
-; CHECK-NEXT: ret i64 [[END_ADDR2]]
+; CHECK-NEXT: ret i64 [[END_ADDR]]
;
%ptr.addr = ptrtoint ptr %ptr to i64
%size = sub i64 %end.addr, %ptr.addr
@@ -20,11 +16,7 @@ define i64 @ptrtoint_gep_sub(ptr %ptr, i64 %end.addr) {
define <2 x i64> @ptrtoint_gep_sub_vector(<2 x ptr> %ptr, <2 x i64> %end.addr) {
; CHECK-LABEL: define <2 x i64> @ptrtoint_gep_sub_vector(
; CHECK-SAME: <2 x ptr> [[PTR:%.*]], <2 x i64> [[END_ADDR:%.*]]) {
-; CHECK-NEXT: [[PTR_ADDR:%.*]] = ptrtoint <2 x ptr> [[PTR]] to <2 x i64>
-; CHECK-NEXT: [[SIZE:%.*]] = sub <2 x i64> [[END_ADDR]], [[PTR_ADDR]]
-; CHECK-NEXT: [[END:%.*]] = getelementptr i8, <2 x ptr> [[PTR]], <2 x i64> [[SIZE]]
-; CHECK-NEXT: [[END_ADDR2:%.*]] = ptrtoint <2 x ptr> [[END]] to <2 x i64>
-; CHECK-NEXT: ret <2 x i64> [[END_ADDR2]]
+; CHECK-NEXT: ret <2 x i64> [[END_ADDR]]
;
%ptr.addr = ptrtoint <2 x ptr> %ptr to <2 x i64>
%size = sub <2 x i64> %end.addr, %ptr.addr
|
dtcxzyw
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nikic
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Oct 16, 2025
InstCombine currently fails to call into InstSimplify for cast instructions. I noticed this because the transform from #98649 can be triggered via `-passes=instsimplify` but not `-passes=instcombine`, which is not supposed to happen.
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…2849) InstCombine currently fails to call into InstSimplify for cast instructions. I noticed this because the transform from llvm/llvm-project#98649 can be triggered via `-passes=instsimplify` but not `-passes=instcombine`, which is not supposed to happen.
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This is a special case of the general ptrtoint(gep) to add(ptrtoint) transform that is particularly profitable, as everything folds away.
Proof: https://alive2.llvm.org/ce/z/fwv8_L
Fixes #86417.