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llvm-project/llvm/test/Transforms/DeadStoreElimination/inter-procedural.ll
Nikita Popov 2d31a12dbe
[DSE] Don't use initializes on byval argument (#126259) 
There are two ways we can fix this problem, depending on how the
semantics of byval and initializes should interact:

* Don't infer initializes on byval arguments. initializes on byval
refers to the original caller memory (or having both attributes is made
a verifier error).
* Infer initializes on byval, but don't use it in DSE. initializes on
byval refers to the callee copy. This matches the semantics of readonly
on byval. This is slightly more powerful, for example, we could do a
backend optimization where byval + initializes will allocate the full
size of byval on the stack but not copy over the parts covered by
initializes.

I went with the second variant here, skipping byval + initializes in DSE
(FunctionAttrs already doesn't propagate initializes past byval). I'm
open to going in the other direction though.

Fixes https://github.com/llvm/llvm-project/issues/126181.
2025-02-10 10:34:03 +01:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -passes=dse -enable-dse-initializes-attr-improvement -S | FileCheck %s
declare void @p1_write_only(ptr nocapture noundef writeonly initializes((0, 2)) dead_on_unwind)
declare void @p1_write_then_read(ptr nocapture noundef initializes((0, 2)) dead_on_unwind)
declare void @p1_clobber(ptr nocapture noundef)
declare void @p2_same_range(ptr nocapture noundef initializes((0, 2)) dead_on_unwind, ptr nocapture noundef initializes((0, 2)) dead_on_unwind)
declare void @p2_no_init(ptr nocapture noundef initializes((0, 2)) dead_on_unwind, ptr nocapture noundef dead_on_unwind)
declare void @p2_no_dead_on_unwind(ptr nocapture noundef initializes((0, 2)) dead_on_unwind, ptr nocapture noundef initializes((0, 2)))
declare void @p2_no_dead_on_unwind_but_nounwind(ptr nocapture noundef initializes((0, 2)) dead_on_unwind, ptr nocapture noundef initializes((0, 2))) nounwind
; Function Attrs: mustprogress nounwind uwtable
define i16 @p1_write_only_caller() {
; CHECK-LABEL: @p1_write_only_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: call void @p1_write_only(ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @p1_write_only(ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p1_write_then_read_caller() {
; CHECK-LABEL: @p1_write_then_read_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: call void @p1_write_then_read(ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @p1_write_then_read(ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
declare void @fn_capture(ptr)
define i16 @p1_write_then_read_caller_escape() {
; CHECK-LABEL: @p1_write_then_read_caller_escape(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: store i16 0, ptr [[PTR]], align 2
; CHECK-NEXT: call void @fn_capture(ptr [[PTR]])
; CHECK-NEXT: call void @p1_write_then_read(ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @fn_capture(ptr %ptr)
call void @p1_write_then_read(ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p1_write_then_read_caller_with_clobber() {
; CHECK-LABEL: @p1_write_then_read_caller_with_clobber(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: store i16 0, ptr [[PTR]], align 2
; CHECK-NEXT: call void @p1_clobber(ptr [[PTR]])
; CHECK-NEXT: call void @p1_write_then_read(ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @p1_clobber(ptr %ptr)
call void @p1_write_then_read(ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
declare void @p1_write_then_read_raw(ptr nocapture noundef initializes((0, 2)))
define i16 @p1_initializes_invoke() personality ptr undef {
; CHECK-LABEL: @p1_initializes_invoke(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: store i16 0, ptr [[PTR]], align 2
; CHECK-NEXT: invoke void @p1_write_then_read_raw(ptr [[PTR]])
; CHECK-NEXT: to label [[BB1:%.*]] unwind label [[BB2:%.*]]
; CHECK: bb1:
; CHECK-NEXT: ret i16 0
; CHECK: bb2:
; CHECK-NEXT: [[TMP:%.*]] = landingpad { ptr, i32 }
; CHECK-NEXT: cleanup
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
entry:
%ptr = alloca i16
store i16 0, ptr %ptr
invoke void @p1_write_then_read_raw(ptr %ptr) to label %bb1 unwind label %bb2
bb1:
ret i16 0
bb2:
%tmp = landingpad { ptr, i32 }
cleanup
%l = load i16, ptr %ptr
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_same_range_noalias_caller() {
; CHECK-LABEL: @p2_same_range_noalias_caller(
; CHECK-NEXT: [[PTR1:%.*]] = alloca i16, align 2
; CHECK-NEXT: [[PTR2:%.*]] = alloca i16, align 2
; CHECK-NEXT: call void @p2_same_range(ptr [[PTR1]], ptr [[PTR2]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR1]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr1 = alloca i16
%ptr2 = alloca i16
store i16 0, ptr %ptr1
store i16 0, ptr %ptr2
call void @p2_same_range(ptr %ptr1, ptr %ptr2)
%l = load i16, ptr %ptr1
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_same_range_must_alias_caller() {
; CHECK-LABEL: @p2_same_range_must_alias_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: call void @p2_same_range(ptr [[PTR]], ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @p2_same_range(ptr %ptr, ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_same_range_may_or_partial_alias_caller1(ptr %base, i1 %x) {
; CHECK-LABEL: @p2_same_range_may_or_partial_alias_caller1(
; CHECK-NEXT: [[BASEPLUS:%.*]] = getelementptr i8, ptr [[BASE:%.*]], i64 1
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[X:%.*]], ptr [[BASEPLUS]], ptr [[BASE]]
; CHECK-NEXT: store i32 0, ptr [[BASE]], align 4
; CHECK-NEXT: call void @p2_same_range(ptr [[BASE]], ptr [[SEL]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[BASE]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%baseplus = getelementptr i8, ptr %base, i64 1
%sel = select i1 %x, ptr %baseplus, ptr %base
store i32 0, ptr %base
call void @p2_same_range(ptr %base, ptr %sel)
%l = load i16, ptr %base
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_same_range_may_or_partial_alias_caller2(ptr %base1, ptr %base2) {
; CHECK-LABEL: @p2_same_range_may_or_partial_alias_caller2(
; CHECK-NEXT: store i32 0, ptr [[BASE1:%.*]], align 4
; CHECK-NEXT: call void @p2_same_range(ptr [[BASE1]], ptr [[BASE2:%.*]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[BASE1]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
store i32 0, ptr %base1
call void @p2_same_range(ptr %base1, ptr %base2)
%l = load i16, ptr %base1
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_no_init_alias_caller() {
; CHECK-LABEL: @p2_no_init_alias_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: store i16 0, ptr [[PTR]], align 2
; CHECK-NEXT: call void @p2_no_init(ptr [[PTR]], ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @p2_no_init(ptr %ptr, ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
; Althrough the 2nd parameter of `p2_no_dead_on_unwind` doesn't have
; the 'dead_on_unwind' attribute, it's invisble to caller on unwind.
; DSE still uses the 'initializes' attribute and kill the dead store.
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_no_dead_on_unwind_but_invisible_to_caller_alias_caller() {
; CHECK-LABEL: @p2_no_dead_on_unwind_but_invisible_to_caller_alias_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: call void @p2_no_dead_on_unwind(ptr [[PTR]], ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @p2_no_dead_on_unwind(ptr %ptr, ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_no_dead_on_unwind_alias_caller(ptr %ptr) {
; CHECK-LABEL: @p2_no_dead_on_unwind_alias_caller(
; CHECK-NEXT: store i16 0, ptr [[PTR:%.*]], align 2
; CHECK-NEXT: call void @p2_no_dead_on_unwind(ptr [[PTR]], ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
store i16 0, ptr %ptr
call void @p2_no_dead_on_unwind(ptr %ptr, ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @p2_no_dead_on_unwind_but_nounwind_alias_caller() {
; CHECK-LABEL: @p2_no_dead_on_unwind_but_nounwind_alias_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca i16, align 2
; CHECK-NEXT: call void @p2_no_dead_on_unwind_but_nounwind(ptr [[PTR]], ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca i16
store i16 0, ptr %ptr
call void @p2_no_dead_on_unwind_but_nounwind(ptr %ptr, ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
declare void @llvm.memset.p0.i64(ptr nocapture, i8, i64, i1) nounwind
declare void @large_p1(ptr nocapture noundef initializes((0, 200))) nounwind
declare void @large_p2(ptr nocapture noundef initializes((0, 200)), ptr nocapture noundef initializes((0, 100))) nounwind
; Function Attrs: mustprogress nounwind uwtable
define i16 @large_p1_caller() {
; CHECK-LABEL: @large_p1_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca [300 x i8], align 1
; CHECK-NEXT: [[TMP:%.*]] = getelementptr i8, ptr [[PTR]], i64 100
; CHECK-NEXT: call void @large_p1(ptr [[TMP]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[TMP]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca [300 x i8]
%tmp = getelementptr i8, ptr %ptr, i64 100
call void @llvm.memset.p0.i64(ptr %tmp, i8 42, i64 100, i1 false)
call void @large_p1(ptr %tmp)
%l = load i16, ptr %tmp
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @large_p2_nonalias_caller() {
; CHECK-LABEL: @large_p2_nonalias_caller(
; CHECK-NEXT: [[PTR1:%.*]] = alloca [200 x i8], align 1
; CHECK-NEXT: [[PTR2:%.*]] = alloca [100 x i8], align 1
; CHECK-NEXT: call void @large_p2(ptr [[PTR1]], ptr [[PTR2]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR1]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr1 = alloca [200 x i8]
%ptr2 = alloca [100 x i8]
call void @llvm.memset.p0.i64(ptr %ptr1, i8 42, i64 200, i1 false)
call void @llvm.memset.p0.i64(ptr %ptr2, i8 42, i64 100, i1 false)
call void @large_p2(ptr %ptr1, ptr %ptr2)
%l = load i16, ptr %ptr1
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @large_p2_must_alias_caller() {
; CHECK-LABEL: @large_p2_must_alias_caller(
; CHECK-NEXT: [[PTR:%.*]] = alloca [300 x i8], align 1
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds i8, ptr [[PTR]], i64 100
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 1 [[TMP1]], i8 42, i64 200, i1 false)
; CHECK-NEXT: call void @large_p2(ptr [[PTR]], ptr [[PTR]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[PTR]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%ptr = alloca [300 x i8]
call void @llvm.memset.p0.i64(ptr %ptr, i8 42, i64 300, i1 false)
call void @large_p2(ptr %ptr, ptr %ptr)
%l = load i16, ptr %ptr
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @large_p2_may_or_partial_alias_caller1(ptr %base) {
; CHECK-LABEL: @large_p2_may_or_partial_alias_caller1(
; CHECK-NEXT: [[BASEPLUS:%.*]] = getelementptr i8, ptr [[BASE:%.*]], i64 100
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr [[BASE]], i8 42, i64 300, i1 false)
; CHECK-NEXT: call void @large_p2(ptr [[BASE]], ptr [[BASEPLUS]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[BASE]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
%baseplus = getelementptr i8, ptr %base, i64 100
call void @llvm.memset.p0.i64(ptr %base, i8 42, i64 300, i1 false)
call void @large_p2(ptr %base, ptr %baseplus)
%l = load i16, ptr %base
ret i16 %l
}
; Function Attrs: mustprogress nounwind uwtable
define i16 @large_p2_may_or_partial_alias_caller2(ptr %base1, ptr %base2) {
; CHECK-LABEL: @large_p2_may_or_partial_alias_caller2(
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr [[BASE1:%.*]], i8 42, i64 300, i1 false)
; CHECK-NEXT: call void @large_p2(ptr [[BASE1]], ptr [[BASE2:%.*]])
; CHECK-NEXT: [[L:%.*]] = load i16, ptr [[BASE1]], align 2
; CHECK-NEXT: ret i16 [[L]]
;
call void @llvm.memset.p0.i64(ptr %base1, i8 42, i64 300, i1 false)
call void @large_p2(ptr %base1, ptr %base2)
%l = load i16, ptr %base1
ret i16 %l
}
@g = global i16 123, align 2
declare void @read_global(ptr nocapture noundef initializes((0, 2))) nounwind
memory(read, argmem: write, inaccessiblemem: none) nounwind
define i16 @global_var_alias() {
; CHECK-LABEL: @global_var_alias(
; CHECK-NEXT: store i16 0, ptr @g, align 4
; CHECK-NEXT: call void @read_global(ptr @g)
; CHECK-NEXT: [[L:%.*]] = load i16, ptr @g, align 2
; CHECK-NEXT: ret i16 [[L]]
;
store i16 0, ptr @g, align 4
call void @read_global(ptr @g)
%l = load i16, ptr @g
ret i16 %l
}
declare void @byval_fn(ptr byval(i32) initializes((0, 4)) %am)
define void @test_byval() {
; CHECK-LABEL: @test_byval(
; CHECK-NEXT: [[A:%.*]] = alloca i32, align 4
; CHECK-NEXT: store i32 0, ptr [[A]], align 4
; CHECK-NEXT: call void @byval_fn(ptr [[A]])
; CHECK-NEXT: ret void
;
%a = alloca i32
store i32 0, ptr %a
call void @byval_fn(ptr %a)
ret void
}
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