1228becf7d
This patch deduces `noundef` attributes for return values. IIUC, a function returns `noundef` values iff all of its return values are guaranteed not to be `undef` or `poison`. Definition of `noundef` from LangRef: ``` noundef This attribute applies to parameters and return values. If the value representation contains any undefined or poison bits, the behavior is undefined. Note that this does not refer to padding introduced by the type’s storage representation. ``` Alive2: https://alive2.llvm.org/ce/z/g8Eis6 Compile-time impact: http://llvm-compile-time-tracker.com/compare.php?from=30dcc33c4ea3ab50397a7adbe85fe977d4a400bd&to=c5e8738d4bfbf1e97e3f455fded90b791f223d74&stat=instructions:u |stage1-O3|stage1-ReleaseThinLTO|stage1-ReleaseLTO-g|stage1-O0-g|stage2-O3|stage2-O0-g|stage2-clang| |--|--|--|--|--|--|--| |+0.01%|+0.01%|-0.01%|+0.01%|+0.03%|-0.04%|+0.01%| The motivation of this patch is to reduce the number of `freeze` insts and enable more optimizations.
78 lines
3.1 KiB
LLVM
78 lines
3.1 KiB
LLVM
; RUN: opt -aa-pipeline=basic-aa -S -passes='default<O2>' < %s | FileCheck %s
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; PR5009
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; CHECK: define noundef i32 @main()
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; CHECK-NEXT: entry:
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; CHECK-NEXT: call void @exit(i32 38)
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
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target triple = "x86_64-apple-darwin10.0.0"
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%struct.cont_t = type { ptr, ptr }
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%struct.foo_sf_t = type { ptr, i32 }
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define i32 @main() nounwind ssp {
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entry:
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%cont = alloca %struct.cont_t, align 8 ; <ptr> [#uses=4]
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%tmp = getelementptr inbounds %struct.cont_t, ptr %cont, i32 0, i32 0 ; <ptr> [#uses=1]
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%tmp1 = getelementptr inbounds %struct.cont_t, ptr %cont, i32 0, i32 0 ; <ptr> [#uses=2]
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store ptr @quit, ptr %tmp1
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%tmp2 = load ptr, ptr %tmp1 ; <ptr> [#uses=1]
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store ptr %tmp2, ptr %tmp
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%tmp3 = getelementptr inbounds %struct.cont_t, ptr %cont, i32 0, i32 1 ; <ptr> [#uses=1]
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store ptr null, ptr %tmp3
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call void @foo(ptr %cont)
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ret i32 0
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}
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define internal void @quit(ptr %cont, i32 %rcode) nounwind ssp {
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entry:
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call void @exit(i32 %rcode) noreturn
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unreachable
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}
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define internal void @foo(ptr %c) nounwind ssp {
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entry:
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%sf = alloca %struct.foo_sf_t, align 8 ; <ptr> [#uses=3]
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%next = alloca %struct.cont_t, align 8 ; <ptr> [#uses=3]
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%tmp = getelementptr inbounds %struct.foo_sf_t, ptr %sf, i32 0, i32 0 ; <ptr> [#uses=1]
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store ptr %c, ptr %tmp
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%tmp2 = getelementptr inbounds %struct.foo_sf_t, ptr %sf, i32 0, i32 1 ; <ptr> [#uses=1]
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store i32 2, ptr %tmp2
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%tmp4 = getelementptr inbounds %struct.cont_t, ptr %next, i32 0, i32 0 ; <ptr> [#uses=1]
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store ptr @foo2, ptr %tmp4
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%tmp5 = getelementptr inbounds %struct.cont_t, ptr %next, i32 0, i32 1 ; <ptr> [#uses=1]
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store ptr %sf, ptr %tmp5
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call void @bar(ptr %next, i32 14)
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ret void
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}
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define internal void @foo2(ptr %sf, i32 %y) nounwind ssp {
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entry:
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%tmp1 = getelementptr inbounds %struct.foo_sf_t, ptr %sf, i32 0, i32 0 ; <ptr> [#uses=1]
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%tmp2 = load ptr, ptr %tmp1 ; <ptr> [#uses=1]
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%tmp3 = getelementptr inbounds %struct.cont_t, ptr %tmp2, i32 0, i32 0 ; <ptr> [#uses=1]
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%tmp4 = load ptr, ptr %tmp3 ; <ptr> [#uses=1]
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%tmp6 = getelementptr inbounds %struct.foo_sf_t, ptr %sf, i32 0, i32 0 ; <ptr> [#uses=1]
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%tmp7 = load ptr, ptr %tmp6 ; <ptr> [#uses=1]
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%tmp9 = getelementptr inbounds %struct.foo_sf_t, ptr %sf, i32 0, i32 1 ; <ptr> [#uses=1]
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%tmp10 = load i32, ptr %tmp9 ; <i32> [#uses=1]
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%mul = mul i32 %tmp10, %y ; <i32> [#uses=1]
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call void %tmp4(ptr %tmp7, i32 %mul)
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ret void
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}
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define internal void @bar(ptr %c, i32 %y) nounwind ssp {
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entry:
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%tmp1 = getelementptr inbounds %struct.cont_t, ptr %c, i32 0, i32 0 ; <ptr> [#uses=1]
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%tmp2 = load ptr, ptr %tmp1 ; <ptr> [#uses=1]
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%tmp4 = getelementptr inbounds %struct.cont_t, ptr %c, i32 0, i32 1 ; <ptr> [#uses=1]
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%tmp5 = load ptr, ptr %tmp4 ; <ptr> [#uses=1]
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%add = add nsw i32 %y, 5 ; <i32> [#uses=1]
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call void %tmp2(ptr %tmp5, i32 %add)
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ret void
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}
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declare void @exit(i32) noreturn
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