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[CaptureTracking] Fix handling for non-returning read-only calls #158979

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Merged
nikic merged 1 commit into from
Sep 17, 2025
+38 −38
Merged

[CaptureTracking] Fix handling for non-returning read-only calls #158979

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18 changes: 9 additions & 9 deletions llvm/lib/Analysis/CaptureTracking.cpp
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Expand Up @@ -275,13 +275,6 @@ UseCaptureInfo llvm::DetermineUseCaptureKind(const Use &U, const Value *Base) {
case Instruction::Call:
case Instruction::Invoke: {
auto *Call = cast<CallBase>(I);
// Not captured if the callee is readonly, doesn't return a copy through
// its return value and doesn't unwind or diverge (a readonly function can
// leak bits by throwing an exception or not depending on the input value).
if (Call->onlyReadsMemory() && Call->doesNotThrow() && Call->willReturn() &&
Call->getType()->isVoidTy())
return CaptureComponents::None;

// The pointer is not captured if returned pointer is not captured.
// NOTE: CaptureTracking users should not assume that only functions
// marked with nocapture do not capture. This means that places like
Expand All @@ -305,10 +298,17 @@ UseCaptureInfo llvm::DetermineUseCaptureKind(const Use &U, const Value *Base) {
if (Call->isCallee(&U))
return CaptureComponents::None;

// Not captured if only passed via 'nocapture' arguments.
assert(Call->isDataOperand(&U) && "Non-callee must be data operand");
CaptureInfo CI = Call->getCaptureInfo(Call->getDataOperandNo(&U));
return UseCaptureInfo(CI.getOtherComponents(), CI.getRetComponents());

// If the call is readonly and doesn't return a value, only the address
// may be captured.
CaptureComponents Mask = CaptureComponents::All;
if (Call->onlyReadsMemory() && Call->getType()->isVoidTy())
Mask = CaptureComponents::Address;

return UseCaptureInfo(CI.getOtherComponents() & Mask,
CI.getRetComponents());
}
case Instruction::Load:
// Volatile loads make the address observable.
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/Other/cgscc-devirt-iteration.ll
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Expand Up @@ -59,7 +59,7 @@ define void @test2_a(ptr %ignore) {
; AFTER1: Function Attrs: nofree memory(read)
; AFTER2: Function Attrs: nofree nosync memory(none)
; BEFORE: define void @test2_a(ptr %ignore)
; AFTER: define void @test2_a(ptr readnone %ignore)
; AFTER: define void @test2_a(ptr readnone captures(address) %ignore)
entry:
%f1ptr = alloca ptr
store ptr @readnone_with_arg, ptr %f1ptr
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/Transforms/Attributor/nocapture-1.ll
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Expand Up @@ -350,7 +350,7 @@ define void @callsite_readonly_nounwind_not_willreturn(ptr %f, ptr %p) {

define void @callsite_readonly_nounwind_willreturn(ptr %f, ptr %p) {
; CHECK-LABEL: define {{[^@]+}}@callsite_readonly_nounwind_willreturn
; CHECK-SAME: (ptr nofree noundef nonnull captures(none) [[F:%.*]], ptr captures(none) [[P:%.*]]) {
; CHECK-SAME: (ptr nofree noundef nonnull captures(none) [[F:%.*]], ptr [[P:%.*]]) {
; CHECK-NEXT: call void [[F]](ptr captures(none) [[P]])
; CHECK-NEXT: ret void
;
Expand Down
14 changes: 7 additions & 7 deletions llvm/test/Transforms/FunctionAttrs/nocapture.ll
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Expand Up @@ -161,7 +161,7 @@ declare void @throw_if_bit_set(ptr, i8) readonly
define i1 @c6(ptr %q, i8 %bit) personality ptr @__gxx_personality_v0 {
; FNATTRS: Function Attrs: nofree memory(read)
; FNATTRS-LABEL: define noundef i1 @c6
; FNATTRS-SAME: (ptr readonly [[Q:%.*]], i8 [[BIT:%.*]]) #[[ATTR5:[0-9]+]] personality ptr @__gxx_personality_v0 {
; FNATTRS-SAME: (ptr readonly captures(address) [[Q:%.*]], i8 [[BIT:%.*]]) #[[ATTR5:[0-9]+]] personality ptr @__gxx_personality_v0 {
; FNATTRS-NEXT: invoke void @throw_if_bit_set(ptr [[Q]], i8 [[BIT]])
; FNATTRS-NEXT: to label [[RET0:%.*]] unwind label [[RET1:%.*]]
; FNATTRS: ret0:
Expand Down Expand Up @@ -364,7 +364,7 @@ declare void @external_not_willreturn(ptr) readonly nounwind
define void @readonly_nounwind_not_willreturn(ptr %p) {
; FNATTRS: Function Attrs: nofree nounwind memory(read)
; FNATTRS-LABEL: define void @readonly_nounwind_not_willreturn
; FNATTRS-SAME: (ptr readonly [[P:%.*]]) #[[ATTR9:[0-9]+]] {
; FNATTRS-SAME: (ptr readonly captures(address) [[P:%.*]]) #[[ATTR9:[0-9]+]] {
; FNATTRS-NEXT: call void @external_not_willreturn(ptr [[P]])
; FNATTRS-NEXT: ret void
;
Expand All @@ -382,7 +382,7 @@ declare void @external_willreturn(ptr) readonly nounwind willreturn
define void @readonly_nounwind_willreturn(ptr %p) {
; FNATTRS: Function Attrs: mustprogress nofree nounwind willreturn memory(read)
; FNATTRS-LABEL: define void @readonly_nounwind_willreturn
; FNATTRS-SAME: (ptr readonly captures(none) [[P:%.*]]) #[[ATTR11:[0-9]+]] {
; FNATTRS-SAME: (ptr readonly captures(address) [[P:%.*]]) #[[ATTR11:[0-9]+]] {
; FNATTRS-NEXT: call void @external_willreturn(ptr [[P]])
; FNATTRS-NEXT: ret void
;
Expand All @@ -398,7 +398,7 @@ define void @readonly_nounwind_willreturn(ptr %p) {

define void @callsite_readonly_nounwind_not_willreturn(ptr %f, ptr %p) {
; FNATTRS-LABEL: define void @callsite_readonly_nounwind_not_willreturn
; FNATTRS-SAME: (ptr readonly captures(none) [[F:%.*]], ptr [[P:%.*]]) {
; FNATTRS-SAME: (ptr readonly captures(none) [[F:%.*]], ptr captures(address) [[P:%.*]]) {
; FNATTRS-NEXT: call void [[F]](ptr [[P]]) #[[ATTR8:[0-9]+]]
; FNATTRS-NEXT: call void [[F]](ptr captures(none) [[P]])
; FNATTRS-NEXT: ret void
Expand All @@ -416,13 +416,13 @@ define void @callsite_readonly_nounwind_not_willreturn(ptr %f, ptr %p) {

define void @callsite_readonly_nounwind_willreturn(ptr %f, ptr %p) {
; FNATTRS-LABEL: define void @callsite_readonly_nounwind_willreturn
; FNATTRS-SAME: (ptr readonly captures(none) [[F:%.*]], ptr captures(none) [[P:%.*]]) {
; FNATTRS-SAME: (ptr readonly captures(none) [[F:%.*]], ptr captures(address) [[P:%.*]]) {
; FNATTRS-NEXT: call void [[F]](ptr [[P]]) #[[ATTR10:[0-9]+]]
; FNATTRS-NEXT: call void [[F]](ptr captures(none) [[P]])
; FNATTRS-NEXT: ret void
;
; ATTRIBUTOR-LABEL: define void @callsite_readonly_nounwind_willreturn
; ATTRIBUTOR-SAME: (ptr nofree nonnull captures(none) [[F:%.*]], ptr captures(none) [[P:%.*]]) {
; ATTRIBUTOR-SAME: (ptr nofree nonnull captures(none) [[F:%.*]], ptr [[P:%.*]]) {
; ATTRIBUTOR-NEXT: call void [[F]](ptr [[P]]) #[[ATTR8:[0-9]+]]
; ATTRIBUTOR-NEXT: call void [[F]](ptr captures(none) [[P]])
; ATTRIBUTOR-NEXT: ret void
Expand Down Expand Up @@ -1032,7 +1032,7 @@ define void @recurse_fptr(ptr %f, ptr %p) {
define void @readnone_indirec(ptr %f, ptr %p) {
; FNATTRS: Function Attrs: nofree nosync memory(none)
; FNATTRS-LABEL: define void @readnone_indirec
; FNATTRS-SAME: (ptr readonly captures(none) [[F:%.*]], ptr readnone [[P:%.*]]) #[[ATTR19:[0-9]+]] {
; FNATTRS-SAME: (ptr readonly captures(none) [[F:%.*]], ptr readnone captures(address) [[P:%.*]]) #[[ATTR19:[0-9]+]] {
; FNATTRS-NEXT: call void [[F]](ptr [[P]]) #[[ATTR23:[0-9]+]]
; FNATTRS-NEXT: ret void
;
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/FunctionAttrs/nonnull.ll
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Expand Up @@ -1032,7 +1032,7 @@ define ptr @g1() {
declare void @use_i32_ptr(ptr) readnone nounwind willreturn
define internal void @called_by_weak(ptr %a) {
; FNATTRS-LABEL: define internal void @called_by_weak(
; FNATTRS-SAME: ptr readnone captures(none) [[A:%.*]]) #[[ATTR10:[0-9]+]] {
; FNATTRS-SAME: ptr readnone captures(address) [[A:%.*]]) #[[ATTR10:[0-9]+]] {
; FNATTRS-NEXT: call void @use_i32_ptr(ptr [[A]])
; FNATTRS-NEXT: ret void
;
Expand Down Expand Up @@ -1064,7 +1064,7 @@ define weak_odr void @weak_caller(ptr nonnull %a) {
; Expect nonnull
define internal void @control(ptr dereferenceable(4) %a) {
; FNATTRS-LABEL: define internal void @control(
; FNATTRS-SAME: ptr readnone captures(none) dereferenceable(4) [[A:%.*]]) #[[ATTR10]] {
; FNATTRS-SAME: ptr readnone captures(address) dereferenceable(4) [[A:%.*]]) #[[ATTR10]] {
; FNATTRS-NEXT: call void @use_i32_ptr(ptr [[A]])
; FNATTRS-NEXT: ret void
;
Expand Down
6 changes: 3 additions & 3 deletions llvm/test/Transforms/FunctionAttrs/out-of-bounds-iterator-bug.ll
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Expand Up @@ -17,14 +17,14 @@ define void @va_func(ptr readonly %b, ...) readonly nounwind willreturn {
}

define i32 @caller(ptr %x) {
; CHECK-LABEL: define noundef i32 @caller(ptr readonly captures(none) %x)
; CHECK-LABEL: define noundef i32 @caller(ptr readonly captures(address) %x)
entry:
call void(ptr,...) @va_func(ptr null, i32 0, i32 0, i32 0, ptr %x)
ret i32 42
}

define void @va_func2(ptr readonly %b, ...) {
; CHECK-LABEL: define void @va_func2(ptr readonly captures(none) %b, ...)
; CHECK-LABEL: define void @va_func2(ptr readonly captures(address) %b, ...)
entry:
%valist = alloca i8
call void @llvm.va_start(ptr %valist)
Expand All @@ -34,7 +34,7 @@ define void @va_func2(ptr readonly %b, ...) {
}

define i32 @caller2(ptr %x, ptr %y) {
; CHECK-LABEL: define noundef i32 @caller2(ptr readonly captures(none) %x, ptr %y)
; CHECK-LABEL: define noundef i32 @caller2(ptr readonly captures(address) %x, ptr %y)
entry:
call void(ptr,...) @va_func2(ptr %x, i32 0, i32 0, i32 0, ptr %y)
ret i32 42
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/FunctionAttrs/readattrs.ll
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Expand Up @@ -483,7 +483,7 @@ define void @fptr_test1b(ptr %p, ptr %f) {
define void @fptr_test1c(ptr %p, ptr %f) {
; FNATTRS: Function Attrs: nofree memory(read)
; FNATTRS-LABEL: define {{[^@]+}}@fptr_test1c
; FNATTRS-SAME: (ptr readnone [[P:%.*]], ptr readonly captures(none) [[F:%.*]]) #[[ATTR3]] {
; FNATTRS-SAME: (ptr readnone captures(address) [[P:%.*]], ptr readonly captures(none) [[F:%.*]]) #[[ATTR3]] {
; FNATTRS-NEXT: call void [[F]](ptr readnone [[P]]) #[[ATTR2:[0-9]+]]
; FNATTRS-NEXT: ret void
;
Expand Down Expand Up @@ -547,7 +547,7 @@ define void @fptr_test2b(ptr %p, ptr %f) {
define void @fptr_test2c(ptr %p, ptr %f) {
; FNATTRS: Function Attrs: nofree memory(read)
; FNATTRS-LABEL: define {{[^@]+}}@fptr_test2c
; FNATTRS-SAME: (ptr readonly [[P:%.*]], ptr readonly captures(none) [[F:%.*]]) #[[ATTR3]] {
; FNATTRS-SAME: (ptr readonly captures(address) [[P:%.*]], ptr readonly captures(none) [[F:%.*]]) #[[ATTR3]] {
; FNATTRS-NEXT: call void [[F]](ptr readonly [[P]]) #[[ATTR2]]
; FNATTRS-NEXT: ret void
;
Expand Down
26 changes: 13 additions & 13 deletions llvm/test/Transforms/LICM/promote-capture.ll
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Expand Up @@ -2,7 +2,7 @@
; RUN: opt -S -passes='loop-mssa(licm)' < %s | FileCheck %s

declare i1 @cond(i32 %v) readnone
declare void @capture(ptr %p) readnone
declare ptr @capture(ptr %p) readnone

define void @test_captured_after_loop(i32 %len) {
; CHECK-LABEL: @test_captured_after_loop(
Expand All @@ -27,7 +27,7 @@ define void @test_captured_after_loop(i32 %len) {
; CHECK: exit:
; CHECK-NEXT: [[C_INC1_LCSSA:%.*]] = phi i32 [ [[C_INC1]], [[LATCH]] ]
; CHECK-NEXT: store i32 [[C_INC1_LCSSA]], ptr [[COUNT]], align 4
; CHECK-NEXT: call void @capture(ptr [[COUNT]])
; CHECK-NEXT: [[TMP0:%.*]] = call ptr @capture(ptr [[COUNT]])
; CHECK-NEXT: ret void
;
entry:
Expand All @@ -52,7 +52,7 @@ latch:
br i1 %cmp, label %exit, label %loop

exit:
call void @capture(ptr %count)
call ptr @capture(ptr %count)
ret void
}

Expand All @@ -71,7 +71,7 @@ define void @test_captured_in_loop(i32 %len) {
; CHECK: if:
; CHECK-NEXT: [[C_INC:%.*]] = add i32 [[C_INC2]], 1
; CHECK-NEXT: store i32 [[C_INC]], ptr [[COUNT]], align 4
; CHECK-NEXT: call void @capture(ptr [[COUNT]])
; CHECK-NEXT: [[TMP0:%.*]] = call ptr @capture(ptr [[COUNT]])
; CHECK-NEXT: br label [[LATCH]]
; CHECK: latch:
; CHECK-NEXT: [[C_INC1]] = phi i32 [ [[C_INC]], [[IF]] ], [ [[C_INC2]], [[LOOP]] ]
Expand All @@ -95,7 +95,7 @@ if:
%c = load i32, ptr %count
%c.inc = add i32 %c, 1
store i32 %c.inc, ptr %count
call void @capture(ptr %count)
call ptr @capture(ptr %count)
br label %latch

latch:
Expand All @@ -112,7 +112,7 @@ define void @test_captured_before_loop(i32 %len) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[COUNT:%.*]] = alloca i32, align 4
; CHECK-NEXT: store i32 0, ptr [[COUNT]], align 4
; CHECK-NEXT: call void @capture(ptr [[COUNT]])
; CHECK-NEXT: [[TMP0:%.*]] = call ptr @capture(ptr [[COUNT]])
; CHECK-NEXT: [[COUNT_PROMOTED:%.*]] = load i32, ptr [[COUNT]], align 4
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
Expand All @@ -135,7 +135,7 @@ define void @test_captured_before_loop(i32 %len) {
entry:
%count = alloca i32
store i32 0, ptr %count
call void @capture(ptr %count)
call ptr @capture(ptr %count)
br label %loop

loop:
Expand Down Expand Up @@ -163,7 +163,7 @@ define void @test_captured_before_loop_address_only(i32 %len) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[COUNT:%.*]] = alloca i32, align 4
; CHECK-NEXT: store i32 0, ptr [[COUNT]], align 4
; CHECK-NEXT: call void @capture(ptr captures(address) [[COUNT]])
; CHECK-NEXT: [[TMP0:%.*]] = call ptr @capture(ptr captures(address) [[COUNT]])
; CHECK-NEXT: [[COUNT_PROMOTED:%.*]] = load i32, ptr [[COUNT]], align 4
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
Expand All @@ -187,7 +187,7 @@ define void @test_captured_before_loop_address_only(i32 %len) {
entry:
%count = alloca i32
store i32 0, ptr %count
call void @capture(ptr captures(address) %count)
call ptr @capture(ptr captures(address) %count)
br label %loop

loop:
Expand Down Expand Up @@ -216,7 +216,7 @@ define void @test_captured_before_loop_byval(ptr byval(i32) align 4 %count, i32
; CHECK-LABEL: @test_captured_before_loop_byval(
; CHECK-NEXT: entry:
; CHECK-NEXT: store i32 0, ptr [[COUNT:%.*]], align 4
; CHECK-NEXT: call void @capture(ptr [[COUNT]])
; CHECK-NEXT: [[TMP0:%.*]] = call ptr @capture(ptr [[COUNT]])
; CHECK-NEXT: [[COUNT_PROMOTED:%.*]] = load i32, ptr [[COUNT]], align 4
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
Expand All @@ -238,7 +238,7 @@ define void @test_captured_before_loop_byval(ptr byval(i32) align 4 %count, i32
;
entry:
store i32 0, ptr %count
call void @capture(ptr %count)
call ptr @capture(ptr %count)
br label %loop

loop:
Expand Down Expand Up @@ -283,7 +283,7 @@ define void @test_captured_after_loop_byval(ptr byval(i32) align 4 %count, i32 %
; CHECK: exit:
; CHECK-NEXT: [[C_INC1_LCSSA:%.*]] = phi i32 [ [[C_INC1]], [[LATCH]] ]
; CHECK-NEXT: store i32 [[C_INC1_LCSSA]], ptr [[COUNT]], align 4
; CHECK-NEXT: call void @capture(ptr [[COUNT]])
; CHECK-NEXT: [[TMP0:%.*]] = call ptr @capture(ptr [[COUNT]])
; CHECK-NEXT: ret void
;
entry:
Expand All @@ -307,6 +307,6 @@ latch:
br i1 %cmp, label %exit, label %loop

exit:
call void @capture(ptr %count)
call ptr @capture(ptr %count)
ret void
}