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| author | Philip Reames <listmail@philipreames.com> | 2018-08-24 16:24:48 +0000 |
|---|---|---|
| committer | Philip Reames <listmail@philipreames.com> | 2018-08-24 16:24:48 +0000 |
| commit | 9ec15faf20a405dffbc83162183822789a534423 (patch) | |
| tree | c8717424dbf6c01efd8815540e184d3bcb76500f | |
| parent | 0f6e12bcdffcec5fcea2133f011b64b52cf8129e (diff) | |
| download | bcm5719-llvm-9ec15faf20a405dffbc83162183822789a534423.tar.gz bcm5719-llvm-9ec15faf20a405dffbc83162183822789a534423.zip | |
[LICM] Hoist an invariant_start out of loops if there are no stores executed before it
Once the invariant_start is reached, we know that no instruction *after* it can modify the memory. So, if we can prove the location isn't read *between entry into the loop and the execution of the invariant_start*, we can execute the invariant_start before entering the loop.
Differential Revision: https://reviews.llvm.org/D51181
llvm-svn: 340617
| -rw-r--r-- | llvm/lib/Transforms/Scalar/LICM.cpp | 4 | ||||
| -rw-r--r-- | llvm/test/Transforms/LICM/invariant.start.ll | 13 |
2 files changed, 9 insertions, 8 deletions
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp index da750d00341..a642d2ef9ff 100644 --- a/llvm/lib/Transforms/Scalar/LICM.cpp +++ b/llvm/lib/Transforms/Scalar/LICM.cpp @@ -525,7 +525,9 @@ bool llvm::hoistRegion(DomTreeNode *N, AliasAnalysis *AA, LoopInfo *LI, } using namespace PatternMatch; - if (match(&I, m_Intrinsic<Intrinsic::experimental_guard>()) && + if (((I.use_empty() && + match(&I, m_Intrinsic<Intrinsic::invariant_start>())) || + match(&I, m_Intrinsic<Intrinsic::experimental_guard>())) && IsMustExecute && IsMemoryNotModified && CurLoop->hasLoopInvariantOperands(&I)) { hoist(I, DT, CurLoop, SafetyInfo, ORE); diff --git a/llvm/test/Transforms/LICM/invariant.start.ll b/llvm/test/Transforms/LICM/invariant.start.ll index 9049e54ab85..d5d44757c40 100644 --- a/llvm/test/Transforms/LICM/invariant.start.ll +++ b/llvm/test/Transforms/LICM/invariant.start.ll @@ -3,19 +3,18 @@ ; RUN: opt -aa-pipeline=basic-aa -licm-n2-threshold=0 -passes='require<aa>,require<targetir>,require<scalar-evolution>,require<opt-remark-emit>,loop(licm)' < %s -S | FileCheck %s ; RUN: opt -aa-pipeline=basic-aa -licm-n2-threshold=200 -passes='require<aa>,require<targetir>,require<scalar-evolution>,require<opt-remark-emit>,loop(licm)' < %s -S | FileCheck %s --check-prefix=ALIAS-N2 -; TODO: By default (without the -licm-n2-threshold value), we should be able to hoist both load and invariant.start define void @test1(i1 %cond, i32* %ptr) { ; CHECK-LABEL: @test1( ; CHECK-LABEL: entry: +; CHECK: call {}* @llvm.invariant.start.p0i32(i64 4, i32* %ptr) ; CHECK: %val = load i32, i32* %ptr ; CHECK-LABEL: loop: -; CHECK: call {}* @llvm.invariant.start.p0i32(i64 4, i32* %ptr) ; ALIAS-N2-LABEL: @test1( ; ALIAS-N2-LABEL: entry: -; ALIAS-N2: %val = load i32, i32* %ptr -; ALIAS-N2-LABEL: loop: ; ALIAS-N2: call {}* @llvm.invariant.start.p0i32(i64 4, i32* %ptr) +; ALIAS-N2: %val = load i32, i32* %ptr +; ALIAS-N2-LABEL: loop: entry: br label %loop @@ -57,15 +56,15 @@ loop: define void @test3(i1 %cond, i32* %ptr) { ; CHECK-LABEL: @test3( ; CHECK-LABEL: entry: +; CHECK: call {}* @llvm.invariant.start.p0i32(i64 4, i32* %ptr) ; CHECK: %val = load i32, i32* %ptr ; CHECK-LABEL: loop: -; CHECK: call {}* @llvm.invariant.start.p0i32(i64 4, i32* %ptr) ; ALIAS-N2-LABEL: @test3( ; ALIAS-N2-LABEL: entry: -; ALIAS-N2: %val = load i32, i32* %ptr +; ALIAS-N2: call {}* @llvm.invariant.start.p0i32(i64 4, i32* %ptr) +; ALIAS-N2: %val = load i32, i32* %ptr ; ALIAS-N2-LABEL: loop: -; ALIAS-N2: call {}* @llvm.invariant.start.p0i32(i64 4, i32* %ptr) entry: br label %loop |
