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author | Florian Hahn <flo@fhahn.com> | 2021-04-28 20:02:47 +0100 |
---|---|---|
committer | Florian Hahn <flo@fhahn.com> | 2021-04-28 20:19:40 +0100 |
commit | 1ed7f8ede564c3b11da4fdca30c36ccbff422576 (patch) | |
tree | 52cc868539bafacc327612a61c632b4449cd86b3 | |
parent | f391de8cb6f9c8ecbd3c6fcf025a2ee203db0726 (diff) | |
download | llvm-1ed7f8ede564c3b11da4fdca30c36ccbff422576.tar.gz |
[LAA] Support pointer phis in loop by analyzing each incoming pointer.
SCEV does not look through non-header PHIs inside the loop. Such phis
can be analyzed by adding separate accesses for each incoming pointer
value.
This results in 2 more loops vectorized in SPEC2000/186.crafty and
avoids regressions when sinking instructions before vectorizing.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D101286
-rw-r--r-- | llvm/lib/Analysis/LoopAccessAnalysis.cpp | 25 | ||||
-rw-r--r-- | llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll | 22 | ||||
-rw-r--r-- | llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll | 9 |
3 files changed, 48 insertions, 8 deletions
diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp index 2a6987848ca5..cd086328ec68 100644 --- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp +++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp @@ -1938,7 +1938,18 @@ void LoopAccessInfo::analyzeLoop(AAResults *AA, LoopInfo *LI, if (blockNeedsPredication(ST->getParent(), TheLoop, DT)) Loc.AATags.TBAA = nullptr; - Accesses.addStore(Loc); + // SCEV does not look through non-header PHIs inside the loop. Such phis + // can be analyzed by adding separate accesses for each incoming pointer + // value. + auto *PN = dyn_cast<PHINode>(Loc.Ptr); + if (PN && TheLoop->contains(PN->getParent()) && + PN->getParent() != TheLoop->getHeader()) { + for (const Use &Inc : PN->incoming_values()) { + MemoryLocation NewLoc = Loc.getWithNewPtr(Inc); + Accesses.addStore(NewLoc); + } + } else + Accesses.addStore(Loc); } } @@ -1982,7 +1993,17 @@ void LoopAccessInfo::analyzeLoop(AAResults *AA, LoopInfo *LI, if (blockNeedsPredication(LD->getParent(), TheLoop, DT)) Loc.AATags.TBAA = nullptr; - Accesses.addLoad(Loc, IsReadOnlyPtr); + // SCEV does not look through non-header PHIs inside the loop. Such phis can + // be analyzed by adding separate accesses for each incoming pointer value. + auto *PN = dyn_cast<PHINode>(Loc.Ptr); + if (PN && TheLoop->contains(PN->getParent()) && + PN->getParent() != TheLoop->getHeader()) { + for (const Use &Inc : PN->incoming_values()) { + MemoryLocation NewLoc = Loc.getWithNewPtr(Inc); + Accesses.addLoad(NewLoc, IsReadOnlyPtr); + } + } else + Accesses.addLoad(Loc, IsReadOnlyPtr); } // If we write (or read-write) to a single destination and there are no diff --git a/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll b/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll index c803825896e9..dcdf6dd6a1fc 100644 --- a/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll +++ b/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll @@ -6,7 +6,7 @@ define i32 @load_with_pointer_phi_no_runtime_checks(%s1* %data) { ; CHECK-LABEL: load_with_pointer_phi_no_runtime_checks ; CHECK-NEXT: loop.header: -; CHECK-NEXT: Report: cannot identify array bounds +; CHECK-NEXT: Memory dependences are safe ; entry: br label %loop.header @@ -41,7 +41,7 @@ exit: ; preds = %loop.latch define i32 @store_with_pointer_phi_no_runtime_checks(%s1* %data) { ; CHECK-LABEL: 'store_with_pointer_phi_no_runtime_checks' ; CHECK-NEXT: loop.header: -; CHECK-NEXT: Report: cannot identify array bounds +; CHECK-NEXT: Memory dependences are safe ; entry: br label %loop.header @@ -76,7 +76,23 @@ exit: ; preds = %loop.latch define i32 @store_with_pointer_phi_runtime_checks(double* %A, double* %B, double* %C) { ; CHECK-LABEL: 'store_with_pointer_phi_runtime_checks' ; CHECK-NEXT: loop.header: -; CHECK-NEXT: Report: cannot identify array bounds +; CHECK-NEXT: Memory dependences are safe with run-time checks +; CHECK: Run-time memory checks: +; CHECK-NEXT: Check 0: +; CHECK-NEXT: Comparing group ([[GROUP_C:.+]]): +; CHECK-NEXT: %gep.2 = getelementptr inbounds double, double* %C, i64 %iv +; CHECK-NEXT: Against group ([[GROUP_B:.+]]): +; CHECK-NEXT: %gep.1 = getelementptr inbounds double, double* %B, i64 %iv +; CHECK-NEXT: Check 1: +; CHECK-NEXT: Comparing group ([[GROUP_C]]): +; CHECK-NEXT: %gep.2 = getelementptr inbounds double, double* %C, i64 %iv +; CHECK-NEXT: Against group ([[GROUP_A:.+]]): +; CHECK-NEXT: %arrayidx = getelementptr inbounds double, double* %A, i64 %iv +; CHECK-NEXT: Check 2: +; CHECK-NEXT: Comparing group ([[GROUP_B]]): +; CHECK-NEXT: %gep.1 = getelementptr inbounds double, double* %B, i64 %iv +; CHECK-NEXT: Against group ([[GROUP_A]]): +; CHECK-NEXT: %arrayidx = getelementptr inbounds double, double* %A, i64 %iv ; entry: br label %loop.header diff --git a/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll b/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll index 53437e3d8c57..e3168d5b5d35 100644 --- a/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll +++ b/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll @@ -4,7 +4,8 @@ define i32 @load_with_pointer_phi_no_runtime_checks(%s1* %data) { ; CHECK-LABEL: @load_with_pointer_phi_no_runtime_checks -; CHECK-NOT: vector.body +; CHECK-NOT: memcheck +; CHECK: vector.body: ; entry: br label %loop.header @@ -38,7 +39,8 @@ exit: ; preds = %loop.latch define i32 @store_with_pointer_phi_no_runtime_checks(%s1* %data) { ; CHECK-LABEL: @store_with_pointer_phi_no_runtime_checks -; CHECK-NOT: vector.body +; CHECK-NOT: memcheck +; CHECK: vector.body ; entry: br label %loop.header @@ -72,7 +74,8 @@ exit: ; preds = %loop.latch define i32 @store_with_pointer_phi_runtime_checks(double* %A, double* %B, double* %C) { ; CHECK-LABEL: @store_with_pointer_phi_runtime_checks -; CHECK-NOT: vector.body +; CHECK: memcheck +; CHECK: vector.body ; entry: br label %loop.header |