diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/EarlyCSE.cpp | 2 | ||||
| -rw-r--r-- | llvm/test/Transforms/EarlyCSE/basic.ll | 38 |
2 files changed, 39 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp index 6f166b8ee7f..cd2ecad4a18 100644 --- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp +++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp @@ -546,7 +546,7 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { Changed = true; ++NumDSE; LastStore = nullptr; - continue; + // fallthrough - we can exploit information about this store } // Okay, we just invalidated anything we knew about loaded values. Try diff --git a/llvm/test/Transforms/EarlyCSE/basic.ll b/llvm/test/Transforms/EarlyCSE/basic.ll index 9f3e474aff9..155d36f60e2 100644 --- a/llvm/test/Transforms/EarlyCSE/basic.ll +++ b/llvm/test/Transforms/EarlyCSE/basic.ll @@ -154,4 +154,42 @@ define i32 @test8(i32 *%P) { ; CHECK: ret i32 0 } +;; Trivial DSE can't be performed across a readonly call. The call +;; can observe the earlier write. +; CHECK-LABEL: @test9( +define i32 @test9(i32 *%P) { + store i32 4, i32* %P + %V1 = call i32 @func(i32* %P) readonly + store i32 5, i32* %P + ret i32 %V1 + ; CHECK: store i32 4, i32* %P + ; CHECK-NEXT: %V1 = call i32 @func(i32* %P) + ; CHECK-NEXT: store i32 5, i32* %P + ; CHECK-NEXT: ret i32 %V1 +} + +;; Trivial DSE can be performed across a readnone call. +; CHECK-LABEL: @test10 +define i32 @test10(i32 *%P) { + store i32 4, i32* %P + %V1 = call i32 @func(i32* %P) readnone + store i32 5, i32* %P + ret i32 %V1 + ; CHECK-NEXT: %V1 = call i32 @func(i32* %P) + ; CHECK-NEXT: store i32 5, i32* %P + ; CHECK-NEXT: ret i32 %V1 +} + +;; Trivial dead store elimination - should work for an entire series of dead stores too. +; CHECK-LABEL: @test11( +define void @test11(i32 *%P) { + store i32 42, i32* %P + store i32 43, i32* %P + store i32 44, i32* %P + store i32 45, i32* %P + ret void + ; CHECK-NEXT: store i32 45 + ; CHECK-NEXT: ret void +} + |
