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.
62 lines
2.7 KiB
LLVM
62 lines
2.7 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
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; RUN: opt -O3 -S < %s | FileCheck %s
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%struct.ss = type { ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }
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define internal void @phantomLoad(ptr %p, ptr %y, ptr %x) {
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entry:
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%0 = load i32, ptr %x
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store i32 %0, ptr %y
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ret void
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}
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define ptr @parent(ptr align 8 dereferenceable(72) %f, half %val1, i16 %val2, i32 %val3) align 2 {
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; CHECK-LABEL: define noundef nonnull ptr @parent
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; CHECK-SAME: (ptr readonly returned align 8 dereferenceable(72) [[F:%.*]], half [[VAL1:%.*]], i16 [[VAL2:%.*]], i32 [[VAL3:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] align 2 {
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds i8, ptr [[F]], i64 64
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; CHECK-NEXT: [[F_VAL:%.*]] = load ptr, ptr [[TMP0]], align 8
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; CHECK-NEXT: [[CMP_NOT_NOT_I:%.*]] = icmp eq i32 [[VAL3]], 0
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; CHECK-NEXT: [[TMP1:%.*]] = bitcast half [[VAL1]] to i16
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; CHECK-NEXT: [[TMP2:%.*]] = bitcast i16 [[VAL2]] to half
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; CHECK-NEXT: [[VAL2_SINK_I:%.*]] = select i1 [[CMP_NOT_NOT_I]], i16 [[TMP1]], i16 [[VAL2]]
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; CHECK-NEXT: [[VAL1_SINK_I:%.*]] = select i1 [[CMP_NOT_NOT_I]], half [[TMP2]], half [[VAL1]]
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; CHECK-NEXT: store i16 [[VAL2_SINK_I]], ptr [[F_VAL]], align 2
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; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[F_VAL]], i64 16
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; CHECK-NEXT: store half [[VAL1_SINK_I]], ptr [[TMP3]], align 2
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; CHECK-NEXT: ret ptr [[F]]
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;
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entry:
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call void @badChild(ptr align 8 dereferenceable(72) %f, half %val1, i16 %val2, i32 %val3) #4
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ret ptr %f
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}
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define internal void @badChild(ptr align 8 dereferenceable(72) %this, half %val1, i16 %val2, i32 %val3) align 2 {
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entry:
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%othergep = getelementptr inbounds %struct.ss, ptr %this, i64 0, i32 2
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%load0 = load ptr, ptr %othergep, align 8
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%x = alloca i32
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%y = alloca i32
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call void @phantomLoad(ptr %load0, ptr %x, ptr %y)
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%val1.cast = bitcast half %val1 to i16
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%cmp.not.not = icmp eq i32 %val3, 0
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br i1 %cmp.not.not, label %if.then, label %if.else
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if.then: ; preds = %entry
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%0 = getelementptr inbounds %struct.ss, ptr %this, i64 0, i32 8
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%1 = load ptr, ptr %0, align 8
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store i16 %val1.cast, ptr %1, align 2
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%add.ptr.i.i.i.i = getelementptr inbounds i8, ptr %1, i64 16
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store i16 %val2, ptr %add.ptr.i.i.i.i, align 2
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br label %if.end
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if.else: ; preds = %entry
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%2 = getelementptr inbounds %struct.ss, ptr %this, i64 0, i32 8
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%3 = load ptr, ptr %2, align 8
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%add.ptr.i.i.i.i7 = getelementptr inbounds i8, ptr %3, i64 16
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store i16 %val1.cast, ptr %add.ptr.i.i.i.i7, align 2
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store i16 %val2, ptr %3, align 2
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br label %if.end
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if.end: ; preds = %if.else, %if.then
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ret void
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}
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