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.
113 lines
4.1 KiB
LLVM
113 lines
4.1 KiB
LLVM
; REQUIRES: x86-registered-target
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; Test that devirtualization option -wholeprogramdevirt-check adds code to check
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; that the devirtualization decision was correct and trap or fallback if not.
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; The vtables have vcall_visibility metadata with hidden visibility, to enable
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; devirtualization.
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; Generate unsplit module with summary for ThinLTO index-based WPD.
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; RUN: opt -thinlto-bc -o %t2.o %s
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; Check first in trapping mode.
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; RUN: llvm-lto2 run %t2.o -save-temps -pass-remarks=. \
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; RUN: -wholeprogramdevirt-check=trap \
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; RUN: -o %t3 \
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; RUN: -r=%t2.o,test,px \
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; RUN: -r=%t2.o,_ZN1A1nEi,p \
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; RUN: -r=%t2.o,_ZN1B1fEi,p \
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; RUN: -r=%t2.o,_ZTV1B,px 2>&1 | FileCheck %s --check-prefix=REMARK
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; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK --check-prefix=TRAP
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; Check next in fallback mode.
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; RUN: llvm-lto2 run %t2.o -save-temps -pass-remarks=. \
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; RUN: -wholeprogramdevirt-check=fallback \
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; RUN: -o %t3 \
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; RUN: -r=%t2.o,test,px \
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; RUN: -r=%t2.o,_ZN1A1nEi,p \
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; RUN: -r=%t2.o,_ZN1B1fEi,p \
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; RUN: -r=%t2.o,_ZTV1B,px 2>&1 | FileCheck %s --check-prefix=REMARK
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; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK --check-prefix=FALLBACK
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; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-grtev4-linux-gnu"
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%struct.A = type { i32 (...)** }
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%struct.B = type { %struct.A }
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@_ZTV1B = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !1, !vcall_visibility !5
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; CHECK-LABEL: define {{(noundef )?}}i32 @test
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define i32 @test(%struct.A* %obj, i32 %a) {
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entry:
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%0 = bitcast %struct.A* %obj to i8***
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%vtable = load i8**, i8*** %0
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%1 = bitcast i8** %vtable to i8*
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%p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
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call void @llvm.assume(i1 %p)
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%fptrptr = getelementptr i8*, i8** %vtable, i32 1
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%2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
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%fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
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; Check that the call was devirtualized, but preceeded by a check guarding
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; a trap if the function pointer doesn't match.
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; TRAP: %.not = icmp eq ptr %fptr1, @_ZN1A1nEi
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; Ensure !prof and !callees metadata for indirect call promotion removed.
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; TRAP-NOT: prof
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; TRAP-NOT: callees
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; TRAP: br i1 %.not, label %1, label %0
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; TRAP: 0:
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; TRAP: tail call void @llvm.debugtrap()
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; TRAP: br label %1
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; TRAP: 1:
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; TRAP: tail call i32 @_ZN1A1nEi
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; Check that the call was devirtualized, but preceeded by a check guarding
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; a fallback if the function pointer doesn't match.
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; FALLBACK: %0 = icmp eq ptr %fptr1, @_ZN1A1nEi
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; FALLBACK: br i1 %0, label %if.true.direct_targ, label %if.false.orig_indirect
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; FALLBACK: if.true.direct_targ:
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; FALLBACK: tail call i32 @_ZN1A1nEi
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; Ensure !prof and !callees metadata for indirect call promotion removed.
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; FALLBACK-NOT: prof
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; FALLBACK-NOT: callees
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; FALLBACK: br label %if.end.icp
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; FALLBACK: if.false.orig_indirect:
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; FALLBACK: tail call i32 %fptr1
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; Ensure !prof and !callees metadata for indirect call promotion removed.
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; In particular, if left on the fallback indirect call ICP may perform an
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; additional round of promotion.
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; FALLBACK-NOT: prof
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; FALLBACK-NOT: callees
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; FALLBACK: br label %if.end.icp
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%call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a), !prof !6, !callees !7
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ret i32 %call
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}
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; CHECK-LABEL: ret i32
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; CHECK-LABEL: }
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declare i1 @llvm.type.test(i8*, metadata)
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declare void @llvm.assume(i1)
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define i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
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ret i32 0;
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}
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define i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
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ret i32 0;
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}
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; Make sure we don't inline or otherwise optimize out the direct calls.
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attributes #0 = { noinline optnone }
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!0 = !{i64 16, !"_ZTS1A"}
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!1 = !{i64 16, !"_ZTS1B"}
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!3 = !{i64 16, !4}
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!4 = distinct !{}
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!5 = !{i64 1}
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!6 = !{!"VP", i32 0, i64 1, i64 1621563287929432257, i64 1}
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!7 = !{i32 (%struct.A*, i32)* @_ZN1A1nEi}
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