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[ConstantFold] Fold inttoptr, ptrtoaddr to bitcast #161087

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Merged
merged 9 commits into from
Sep 29, 2025
Merged

[ConstantFold] Fold inttoptr, ptrtoaddr to bitcast #161087

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267d813
[ConstantFold] inttoptr, ptrtoaddr is valid cast pair
XChy Sep 28, 2025
5513266
optimize inttoptr, ptrtoaddr
XChy Sep 28, 2025
fbdea3c
fix testcases
XChy Sep 28, 2025
7ac9346
format
XChy Sep 28, 2025
d6fda59
fix typo
XChy Sep 28, 2025
b1ccc78
fix typo
XChy Sep 28, 2025
9eb64c9
add tests
XChy Sep 29, 2025
d451c18
add address space
XChy Sep 29, 2025
1101f3b
move tests
XChy Sep 29, 2025
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6 changes: 4 additions & 2 deletions llvm/lib/IR/Instructions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2847,6 +2847,7 @@ unsigned CastInst::isEliminableCastPair(
// FPTRUNC > FloatPt n/a FloatPt n/a
// FPEXT < FloatPt n/a FloatPt n/a
// PTRTOINT n/a Pointer n/a Integral Unsigned
// PTRTOADDR n/a Pointer n/a Integral Unsigned
// INTTOPTR n/a Integral Unsigned Pointer n/a
// BITCAST = FirstClass n/a FirstClass n/a
// ADDRSPCST n/a Pointer n/a Pointer n/a
Expand Down Expand Up @@ -2878,7 +2879,7 @@ unsigned CastInst::isEliminableCastPair(
{ 99,99,99, 2, 2,99,99, 8, 2,99,99,99, 4, 0}, // FPExt |
{ 1, 0, 0,99,99, 0, 0,99,99,99,99, 7, 3, 0}, // PtrToInt |
{ 1, 0, 0,99,99, 0, 0,99,99,99,99, 0, 3, 0}, // PtrToAddr |
{ 99,99,99,99,99,99,99,99,99,11,99,99,15, 0}, // IntToPtr |
{ 99,99,99,99,99,99,99,99,99,11,11,99,15, 0}, // IntToPtr |
{ 5, 5, 5, 0, 0, 5, 5, 0, 0,16,16, 5, 1,14}, // BitCast |
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,13,12}, // AddrSpaceCast -+
};
Expand Down Expand Up @@ -2972,7 +2973,8 @@ unsigned CastInst::isEliminableCastPair(
// zext, sext -> zext, because sext can't sign extend after zext
return Instruction::ZExt;
case 11: {
// inttoptr, ptrtoint -> bitcast if SrcSize<=PtrSize and SrcSize==DstSize
// inttoptr, ptrtoint/ptrtoaddr -> bitcast if SrcSize<=PtrSize and
// SrcSize==DstSize
if (!MidIntPtrTy)
return 0;
unsigned PtrSize = MidIntPtrTy->getScalarSizeInBits();
Expand Down
65 changes: 65 additions & 0 deletions llvm/test/Transforms/InstCombine/ptrtoaddr.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,65 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
target datalayout = "p1:64:64:64:32"

define i32 @ptrtoaddr_inttoptr_arg(i32 %a) {
; CHECK-LABEL: define i32 @ptrtoaddr_inttoptr_arg(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[A]] to i64
; CHECK-NEXT: [[TOPTR:%.*]] = inttoptr i64 [[TMP1]] to ptr addrspace(1)
; CHECK-NEXT: [[TOADDR:%.*]] = ptrtoaddr ptr addrspace(1) [[TOPTR]] to i32
; CHECK-NEXT: ret i32 [[TOADDR]]
;
%toptr = inttoptr i32 %a to ptr addrspace(1)
%toaddr = ptrtoaddr ptr addrspace(1) %toptr to i32
ret i32 %toaddr
}

define i32 @ptrtoaddr_inttoptr() {
; CHECK-LABEL: define i32 @ptrtoaddr_inttoptr() {
; CHECK-NEXT: ret i32 -1
;
ret i32 ptrtoaddr (ptr addrspace(1) inttoptr (i32 -1 to ptr addrspace(1)) to i32)
}

define i32 @ptrtoaddr_inttoptr_diff_size1() {
; CHECK-LABEL: define i32 @ptrtoaddr_inttoptr_diff_size1() {
; CHECK-NEXT: ret i32 ptrtoaddr (ptr addrspace(1) inttoptr (i64 -1 to ptr addrspace(1)) to i32)
;
ret i32 ptrtoaddr (ptr addrspace(1) inttoptr (i64 -1 to ptr addrspace(1)) to i32)
}

define i32 @ptrtoaddr_inttoptr_diff_size2() {
; CHECK-LABEL: define i32 @ptrtoaddr_inttoptr_diff_size2() {
; CHECK-NEXT: ret i32 ptrtoaddr (ptr addrspace(1) inttoptr (i16 -1 to ptr addrspace(1)) to i32)
;
ret i32 ptrtoaddr (ptr addrspace(1) inttoptr (i16 -1 to ptr addrspace(1)) to i32)
}
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Hm, we can make some of these fold, but we should really change the isEliminableCastPair() API to accept DataLayout for that. Leaving these cases alone is fine for now.


define i64 @ptrtoaddr_inttoptr_noas1() {
; CHECK-LABEL: define i64 @ptrtoaddr_inttoptr_noas1() {
; CHECK-NEXT: ret i64 1
;
ret i64 ptrtoaddr (ptr getelementptr (i8, ptr null, i64 1) to i64)
}

define i64 @ptr2addr2_inttoptr_noas2() {
; CHECK-LABEL: define i64 @ptr2addr2_inttoptr_noas2() {
; CHECK-NEXT: ret i64 123
;
ret i64 ptrtoaddr (ptr inttoptr (i64 123 to ptr) to i64)
}

define i64 @ptrtoaddr_inttoptr_noas_diff_size1() {
; CHECK-LABEL: define i64 @ptrtoaddr_inttoptr_noas_diff_size1() {
; CHECK-NEXT: ret i64 ptrtoaddr (ptr inttoptr (i32 -1 to ptr) to i64)
;
ret i64 ptrtoaddr (ptr inttoptr (i32 -1 to ptr) to i64)
}

define i64 @ptrtoaddr_inttoptr_noas_diff_size2() {
; CHECK-LABEL: define i64 @ptrtoaddr_inttoptr_noas_diff_size2() {
; CHECK-NEXT: ret i64 ptrtoaddr (ptr inttoptr (i128 -1 to ptr) to i64)
;
ret i64 ptrtoaddr (ptr inttoptr (i128 -1 to ptr) to i64)
}