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https://github.com/c64scene-ar/llvm-6502.git
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c89c6a964c
straight-forward implementation. This does not require any extra alias analysis queries beyond what we already do for non-local loads. Some programs really really like load PRE. For example, SPASS triggers this ~1000 times, ~300 times in 255.vortex, and ~1500 times on 403.gcc. The biggest limitation to the implementation is that it does not split critical edges. This is a huge killer on many programs and should be addressed after the initial patch is enabled by default. The implementation of this should incidentally speed up rejection of non-local loads because it avoids creating the repl densemap in cases when it won't be used for fully redundant loads. This is currently disabled by default. Before I turn this on, I need to fix a couple of miscompilations in the testsuite, look at compile time performance numbers, and look at perf impact. This is pretty close to ready though. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60408 91177308-0d34-0410-b5e6-96231b3b80d8
19 lines
322 B
LLVM
19 lines
322 B
LLVM
; RUN: llvm-as < %s | opt -gvn -enable-load-pre | llvm-dis | grep {%PRE.rle = phi}
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define i32 @test(i32* %p, i1 %C) {
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block1:
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br i1 %C, label %block2, label %block3
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block2:
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br label %block4
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block3:
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%b = bitcast i32 0 to i32
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store i32 %b, i32* %p
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br label %block4
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block4:
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%PRE = load i32* %p
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ret i32 %PRE
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}
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