diff options
| -rw-r--r-- | llvm/lib/Target/README.txt | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/llvm/lib/Target/README.txt b/llvm/lib/Target/README.txt index 4e4668698ad..756f38a6491 100644 --- a/llvm/lib/Target/README.txt +++ b/llvm/lib/Target/README.txt @@ -1651,3 +1651,25 @@ globalopt to remove the "stored only" global. //===---------------------------------------------------------------------===// +This code: + +define inreg i32 @foo(i8* inreg %p) nounwind { + %tmp0 = load i8* %p + %tmp1 = ashr i8 %tmp0, 5 + %tmp2 = sext i8 %tmp1 to i32 + ret i32 %tmp2 +} + +could be dagcombine'd to a sign-extending load with a shift. +For example, on x86 this currently gets this: + + movb (%eax), %al + sarb $5, %al + movsbl %al, %eax + +while it could get this: + + movsbl (%eax), %eax + sarl $5, %eax + +//===---------------------------------------------------------------------===// |
