llvm-6502/test/Transforms/InstCombine/shift-simplify.ll
Chris Lattner 4241e4da85 Implement shift-simplify.ll:test[45].
First teach instcombine that sign bit checks only demand the 
sign bit, this allows simplify demanded bits to hack on 
expressions better.

Second, teach instcombine that ashr is useless if only the
sign bit is demanded.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39880 91177308-0d34-0410-b5e6-96231b3b80d8
2007-07-15 20:54:51 +00:00

43 lines
832 B
LLVM

; RUN: llvm-as < %s | opt -instcombine | llvm-dis | \
; RUN: egrep {shl|lshr|ashr} | wc -l | grep 3
define i32 @test0(i32 %A, i32 %B, i32 %C) {
%X = shl i32 %A, %C
%Y = shl i32 %B, %C
%Z = and i32 %X, %Y
ret i32 %Z
}
define i32 @test1(i32 %A, i32 %B, i32 %C) {
%X = lshr i32 %A, %C
%Y = lshr i32 %B, %C
%Z = or i32 %X, %Y
ret i32 %Z
}
define i32 @test2(i32 %A, i32 %B, i32 %C) {
%X = ashr i32 %A, %C
%Y = ashr i32 %B, %C
%Z = xor i32 %X, %Y
ret i32 %Z
}
define i1 @test3(i32 %X) {
%tmp1 = shl i32 %X, 7
%tmp2 = icmp slt i32 %tmp1, 0
ret i1 %tmp2
}
define i1 @test4(i32 %X) {
%tmp1 = lshr i32 %X, 7
%tmp2 = icmp slt i32 %tmp1, 0
ret i1 %tmp2
}
define i1 @test5(i32 %X) {
%tmp1 = ashr i32 %X, 7
%tmp2 = icmp slt i32 %tmp1, 0
ret i1 %tmp2
}