target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64--linux" @str = constant [6 x i8] c"foobar" declare { ptr, i64, i64 } @runtime.stringToBytes(ptr, i64) declare void @printSlice(ptr nocapture readonly, i64, i64) declare void @writeToSlice(ptr nocapture, i64, i64) ; Test that runtime.stringToBytes can be fully optimized away. define void @testReadOnly() { entry: %0 = call fastcc { ptr, i64, i64 } @runtime.stringToBytes(ptr @str, i64 6) %1 = extractvalue { ptr, i64, i64 } %0, 0 %2 = extractvalue { ptr, i64, i64 } %0, 1 %3 = extractvalue { ptr, i64, i64 } %0, 2 call fastcc void @printSlice(ptr %1, i64 %2, i64 %3) ret void } ; Test that even though the slice is written to, some values can be propagated. define void @testReadWrite() { entry: %0 = call fastcc { ptr, i64, i64 } @runtime.stringToBytes(ptr @str, i64 6) %1 = extractvalue { ptr, i64, i64 } %0, 0 %2 = extractvalue { ptr, i64, i64 } %0, 1 %3 = extractvalue { ptr, i64, i64 } %0, 2 call fastcc void @writeToSlice(ptr %1, i64 %2, i64 %3) ret void }