[llvm] ebe741f - [DSE] Enable initializes improvement (#119116)

[via llvm-commits]

Author: Haopeng Liu
Date: 2024-12-10T09:58:13-08:00
New Revision: ebe741fad07e3fda388d0fa44f256a07429cce6a

URL: https://github.com/llvm/llvm-project/commit/ebe741fad07e3fda388d0fa44f256a07429cce6a
DIFF: https://github.com/llvm/llvm-project/commit/ebe741fad07e3fda388d0fa44f256a07429cce6a.diff

LOG: [DSE] Enable initializes improvement (#119116)

Tested with an internal search backend loadtest.

With `-ftrivial-auto-var-init`, this work has a 0.2%-0.3% total QPS
improvement.

Note that, the metric is total QPS instead of cpu-time, even 1%
improvement means a lot.

- Add the "initializes" attr:
https://github.com/llvm/llvm-project/pull/97373
- Apply the attr to DSE:
https://github.com/llvm/llvm-project/pull/107282

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index 09e8301b772d96..778f83b7925691 100644
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -164,9 +164,9 @@ static cl::opt<bool>
     OptimizeMemorySSA("dse-optimize-memoryssa", cl::init(true), cl::Hidden,
                       cl::desc("Allow DSE to optimize memory accesses."));
 
-// TODO: turn on and remove this flag.
+// TODO: remove this flag.
 static cl::opt<bool> EnableInitializesImprovement(
-    "enable-dse-initializes-attr-improvement", cl::init(false), cl::Hidden,
+    "enable-dse-initializes-attr-improvement", cl::init(true), cl::Hidden,
     cl::desc("Enable the initializes attr improvement in DSE"));
 
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