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llvm-project/llvm/test/Analysis/MemorySSA/pr43317.ll

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[MemorySSA] Avoid adding Phis in the presence of unreachable blocks. Summary: If a block has all incoming values with the same MemoryAccess (ignoring incoming values from unreachable blocks), then use that incoming MemoryAccess and do not create a Phi in the first place. Revert IDF work-around added in rL372673; it should not be required unless the Def inserted is the first in its block. The patch also cleans up a series of tests, added during the many iterations on insertDef. The patch also fixes PR43438. The same issue that occurs in insertDef with "adding phis, hence the IDF of Phis is needed", can also occur in fixupDefs: the `getPreviousRecursive` call only adds Phis walking on the predecessor edges, which means there may be the case of a Phi added walking the CFG "backwards" which triggers the needs for an additional Phi in successor blocks. Such Phis are added during fixupDefs only in the presence of unreachable blocks. Hence this highlights the need to avoid adding Phis in blocks with unreachable predecessors in the first place. Reviewers: george.burgess.iv Subscribers: Prazek, sanjoy.google, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67995 llvm-svn: 372932
2019-09-26 07:24:39 +08:00
; RUN: opt -disable-output -licm -print-memoryssa -enable-mssa-loop-dependency=true < %s 2>&1 | FileCheck %s
[MemorySSA] Update Phi insertion. Summary: MemoryPhis may be needed following a Def insertion inthe IDF of all the new accesses added (phis + potentially a def). Ensure this also occurs when only the new MemoryPhis are the defining accesses. Note: The need for computing IDF here is because of new Phis added with edges incoming from unreachable code, Phis that had previously been simplified. The preferred solution is to not reintroduce such Phis. This patch is the needed fix while working on the preferred solution. Reviewers: george.burgess.iv Subscribers: Prazek, sanjoy.google, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67927 llvm-svn: 372673
2019-09-24 07:50:16 +08:00
@v_274 = external dso_local global i64, align 1
@v_295 = external dso_local global i16, align 1
@v_335 = external dso_local global i32, align 1
; CHECK-LABEL: @main()
[MemorySSA] Avoid adding Phis in the presence of unreachable blocks. Summary: If a block has all incoming values with the same MemoryAccess (ignoring incoming values from unreachable blocks), then use that incoming MemoryAccess and do not create a Phi in the first place. Revert IDF work-around added in rL372673; it should not be required unless the Def inserted is the first in its block. The patch also cleans up a series of tests, added during the many iterations on insertDef. The patch also fixes PR43438. The same issue that occurs in insertDef with "adding phis, hence the IDF of Phis is needed", can also occur in fixupDefs: the `getPreviousRecursive` call only adds Phis walking on the predecessor edges, which means there may be the case of a Phi added walking the CFG "backwards" which triggers the needs for an additional Phi in successor blocks. Such Phis are added during fixupDefs only in the presence of unreachable blocks. Hence this highlights the need to avoid adding Phis in blocks with unreachable predecessors in the first place. Reviewers: george.burgess.iv Subscribers: Prazek, sanjoy.google, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67995 llvm-svn: 372932
2019-09-26 07:24:39 +08:00
; CHECK-NOT: 5 = MemoryPhi(
; CHECK-NOT: 6 = MemoryPhi(
; CHECK: 4 = MemoryPhi(
; CHECK-NOT: 7 = MemoryPhi(
[MemorySSA] Update Phi insertion. Summary: MemoryPhis may be needed following a Def insertion inthe IDF of all the new accesses added (phis + potentially a def). Ensure this also occurs when only the new MemoryPhis are the defining accesses. Note: The need for computing IDF here is because of new Phis added with edges incoming from unreachable code, Phis that had previously been simplified. The preferred solution is to not reintroduce such Phis. This patch is the needed fix while working on the preferred solution. Reviewers: george.burgess.iv Subscribers: Prazek, sanjoy.google, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67927 llvm-svn: 372673
2019-09-24 07:50:16 +08:00
define dso_local void @main() {
entry:
store i32 undef, i32* @v_335, align 1
br i1 undef, label %gate, label %exit
nopredentry1: ; No predecessors!
br label %preinfiniteloop
nopredentry2: ; No predecessors!
br label %gate
gate: ; preds = %nopredentry2, %entry
br i1 undef, label %preinfiniteloop, label %exit
preinfiniteloop: ; preds = %gate, %nopredentry1
br label %infiniteloop
infiniteloop: ; preds = %infiniteloop, %preinfiniteloop
store i16 undef, i16* @v_295, align 1
br label %infiniteloop
exit: ; preds = %gate, %entry
store i64 undef, i64* @v_274, align 1
ret void
}