5f30897b7b
This patch updates MemorySSA's use-optimizing walker to be more accurate and, in some cases, faster. Essentially, this changed our core walking algorithm from a cache-as-you-go DFS to an iteratively expanded DFS, with all of the caching happening at the end. Said expansion happens when we hit a Phi, P; we'll try to do the smallest amount of work possible to see if optimizing above that Phi is legal in the first place. If so, we'll expand the search to see if we can optimize to the next phi, etc. An iteratively expanded DFS lets us potentially quit earlier (because we don't assume that we can optimize above all phis) than our old walker. Additionally, because we don't cache as we go, we can now optimize above loops. As an added bonus, this patch adds a ton of verification (if EXPENSIVE_CHECKS are enabled), so finding bugs is easier. Differential Revision: https://reviews.llvm.org/D21777 llvm-svn: 275940
182 lines
4.5 KiB
LLVM
182 lines
4.5 KiB
LLVM
; RUN: opt -basicaa -print-memoryssa -verify-memoryssa -analyze < %s 2>&1 | FileCheck %s
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; RUN: opt -aa-pipeline=basic-aa -passes='print<memoryssa>,verify<memoryssa>' -disable-output < %s 2>&1 | FileCheck %s
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; %ptr can't alias %local, so we should be able to optimize the use of %local to
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; point to the store to %local.
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; CHECK-LABEL: define void @check
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define void @check(i8* %ptr, i1 %bool) {
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entry:
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%local = alloca i8, align 1
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; CHECK: 1 = MemoryDef(liveOnEntry)
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; CHECK-NEXT: store i8 0, i8* %local, align 1
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store i8 0, i8* %local, align 1
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br i1 %bool, label %if.then, label %if.end
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if.then:
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%p2 = getelementptr inbounds i8, i8* %ptr, i32 1
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; CHECK: 2 = MemoryDef(1)
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; CHECK-NEXT: store i8 0, i8* %p2, align 1
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store i8 0, i8* %p2, align 1
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br label %if.end
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if.end:
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; CHECK: 3 = MemoryPhi({entry,1},{if.then,2})
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; CHECK: MemoryUse(1)
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; CHECK-NEXT: load i8, i8* %local, align 1
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load i8, i8* %local, align 1
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ret void
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}
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; CHECK-LABEL: define void @check2
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define void @check2(i1 %val1, i1 %val2, i1 %val3) {
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entry:
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%local = alloca i8, align 1
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%local2 = alloca i8, align 1
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; CHECK: 1 = MemoryDef(liveOnEntry)
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; CHECK-NEXT: store i8 0, i8* %local
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store i8 0, i8* %local
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br i1 %val1, label %if.then, label %phi.3
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if.then:
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; CHECK: 2 = MemoryDef(1)
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; CHECK-NEXT: store i8 2, i8* %local2
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store i8 2, i8* %local2
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br i1 %val2, label %phi.2, label %phi.3
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phi.3:
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; CHECK: 6 = MemoryPhi({entry,1},{if.then,2})
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; CHECK: 3 = MemoryDef(6)
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; CHECK-NEXT: store i8 3, i8* %local2
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store i8 3, i8* %local2
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br i1 %val3, label %phi.2, label %phi.1
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phi.2:
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; CHECK: 5 = MemoryPhi({if.then,2},{phi.3,3})
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; CHECK: 4 = MemoryDef(5)
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; CHECK-NEXT: store i8 4, i8* %local2
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store i8 4, i8* %local2
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br label %phi.1
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phi.1:
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; Order matters here; phi.2 needs to come before phi.3, because that's the order
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; they're visited in.
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; CHECK: 7 = MemoryPhi({phi.2,4},{phi.3,3})
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; CHECK: MemoryUse(1)
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; CHECK-NEXT: load i8, i8* %local
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load i8, i8* %local
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ret void
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}
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; CHECK-LABEL: define void @cross_phi
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define void @cross_phi(i8* noalias %p1, i8* noalias %p2) {
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; CHECK: 1 = MemoryDef(liveOnEntry)
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; CHECK-NEXT: store i8 0, i8* %p1
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store i8 0, i8* %p1
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; CHECK: MemoryUse(1)
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; CHECK-NEXT: load i8, i8* %p1
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load i8, i8* %p1
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br i1 undef, label %a, label %b
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a:
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; CHECK: 2 = MemoryDef(1)
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; CHECK-NEXT: store i8 0, i8* %p2
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store i8 0, i8* %p2
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br i1 undef, label %c, label %d
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b:
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; CHECK: 3 = MemoryDef(1)
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; CHECK-NEXT: store i8 1, i8* %p2
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store i8 1, i8* %p2
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br i1 undef, label %c, label %d
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c:
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; CHECK: 6 = MemoryPhi({a,2},{b,3})
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; CHECK: 4 = MemoryDef(6)
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; CHECK-NEXT: store i8 2, i8* %p2
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store i8 2, i8* %p2
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br label %e
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d:
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; CHECK: 7 = MemoryPhi({a,2},{b,3})
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; CHECK: 5 = MemoryDef(7)
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; CHECK-NEXT: store i8 3, i8* %p2
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store i8 3, i8* %p2
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br label %e
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e:
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; 8 = MemoryPhi({c,4},{d,5})
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; CHECK: MemoryUse(1)
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; CHECK-NEXT: load i8, i8* %p1
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load i8, i8* %p1
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ret void
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}
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; CHECK-LABEL: define void @looped
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define void @looped(i8* noalias %p1, i8* noalias %p2) {
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; CHECK: 1 = MemoryDef(liveOnEntry)
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; CHECK-NEXT: store i8 0, i8* %p1
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store i8 0, i8* %p1
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br label %loop.1
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loop.1:
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; CHECK: 7 = MemoryPhi({%0,1},{loop.3,4})
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; CHECK: 2 = MemoryDef(7)
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; CHECK-NEXT: store i8 0, i8* %p2
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store i8 0, i8* %p2
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br i1 undef, label %loop.2, label %loop.3
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loop.2:
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; CHECK: 6 = MemoryPhi({loop.1,2},{loop.3,4})
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; CHECK: 3 = MemoryDef(6)
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; CHECK-NEXT: store i8 1, i8* %p2
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store i8 1, i8* %p2
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br label %loop.3
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loop.3:
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; CHECK: 5 = MemoryPhi({loop.1,2},{loop.2,3})
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; CHECK: 4 = MemoryDef(5)
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; CHECK-NEXT: store i8 2, i8* %p2
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store i8 2, i8* %p2
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; CHECK: MemoryUse(1)
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; CHECK-NEXT: load i8, i8* %p1
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load i8, i8* %p1
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br i1 undef, label %loop.2, label %loop.1
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}
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; CHECK-LABEL: define void @looped_visitedonlyonce
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define void @looped_visitedonlyonce(i8* noalias %p1, i8* noalias %p2) {
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br label %while.cond
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while.cond:
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; CHECK: 5 = MemoryPhi({%0,liveOnEntry},{if.end,3})
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; CHECK-NEXT: br i1 undef, label %if.then, label %if.end
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br i1 undef, label %if.then, label %if.end
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if.then:
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; CHECK: 1 = MemoryDef(5)
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; CHECK-NEXT: store i8 0, i8* %p1
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store i8 0, i8* %p1
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br i1 undef, label %if.end, label %if.then2
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if.then2:
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; CHECK: 2 = MemoryDef(1)
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; CHECK-NEXT: store i8 1, i8* %p2
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store i8 1, i8* %p2
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br label %if.end
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if.end:
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; CHECK: 4 = MemoryPhi({while.cond,5},{if.then,1},{if.then2,2})
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; CHECK: MemoryUse(4)
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; CHECK-NEXT: load i8, i8* %p1
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load i8, i8* %p1
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; CHECK: 3 = MemoryDef(4)
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; CHECK-NEXT: store i8 2, i8* %p2
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store i8 2, i8* %p2
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; CHECK: MemoryUse(4)
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; CHECK-NEXT: load i8, i8* %p1
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load i8, i8* %p1
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br label %while.cond
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}
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