65beddafe8
Unfortunately, while doing this I found that it doesn't actually apply in any real-world programs (tested with `make smoketest`), apparently because nil pointer checking messes with the functionattrs pass. I hope to fix that after moving to LLVM 9, which has an optimization that makes nil pointer checking easier to implement.
32 строки
1,2 КиБ
LLVM
32 строки
1,2 КиБ
LLVM
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64--linux"
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@str = constant [6 x i8] c"foobar"
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declare { i8*, i64, i64 } @runtime.stringToBytes(i8*, i64)
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declare void @printSlice(i8* nocapture readonly, i64, i64)
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declare void @writeToSlice(i8* nocapture, i64, i64)
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; Test that runtime.stringToBytes can be fully optimized away.
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define void @testReadOnly() {
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entry:
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%0 = call fastcc { i8*, i64, i64 } @runtime.stringToBytes(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @str, i32 0, i32 0), i64 6)
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%1 = extractvalue { i8*, i64, i64 } %0, 0
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%2 = extractvalue { i8*, i64, i64 } %0, 1
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%3 = extractvalue { i8*, i64, i64 } %0, 2
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call fastcc void @printSlice(i8* %1, i64 %2, i64 %3)
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ret void
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}
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; Test that even though the slice is written to, some values can be propagated.
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define void @testReadWrite() {
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entry:
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%0 = call fastcc { i8*, i64, i64 } @runtime.stringToBytes(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @str, i32 0, i32 0), i64 6)
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%1 = extractvalue { i8*, i64, i64 } %0, 0
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%2 = extractvalue { i8*, i64, i64 } %0, 1
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%3 = extractvalue { i8*, i64, i64 } %0, 2
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call fastcc void @writeToSlice(i8* %1, i64 %2, i64 %3)
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ret void
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}
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