[llvm] [DSE] Apply initializes attribute to DSE (PR #107282)

[Jan Voung via llvm-commits]

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@@ -0,0 +1,272 @@
+; 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
+}
+
+; 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
+}
+
+; 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_invisble_to_caller_alias_caller() {
+; CHECK-LABEL: @p2_no_dead_on_unwind_but_invisble_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
+}
----------------
jvoung wrote:

Might be good to have a test case like aeubanks had in the comments, with `invoke` where the arg points to an alloca and there is a `load` in the `unwind label %bb2`?

https://github.com/llvm/llvm-project/pull/107282