llvm/test/CodeGen/X86/or-lea.ll
Matthias Braun 79519fecc3 VirtRegMap: Replace some identity copies with KILL instructions.
An identity COPY like this:
   %AL = COPY %AL, %EAX<imp-def>
has no semantic effect, but encodes liveness information: Further users
of %EAX only depend on this instruction even though it does not define
the full register.

Replace the COPY with a KILL instruction in those cases to maintain this
liveness information. (This reverts a small part of r238588 but this
time adds a comment explaining why a KILL instruction is useful).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274952 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-09 00:19:07 +00:00

134 lines
3.5 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
; InstCombine and DAGCombiner transform an 'add' into an 'or'
; if there are no common bits from the incoming operands.
; LEA instruction selection should be able to see through that
; transform and reduce add/shift/or instruction counts.
define i32 @or_shift1_and1(i32 %x, i32 %y) {
; CHECK-LABEL: or_shift1_and1:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %ESI<def> %ESI<kill> %RSI<def>
; CHECK-NEXT: # kill: %EDI<def> %EDI<kill> %RDI<def>
; CHECK-NEXT: andl $1, %esi
; CHECK-NEXT: leal (%rsi,%rdi,2), %eax
; CHECK-NEXT: retq
%shl = shl i32 %x, 1
%and = and i32 %y, 1
%or = or i32 %and, %shl
ret i32 %or
}
define i32 @or_shift1_and1_swapped(i32 %x, i32 %y) {
; CHECK-LABEL: or_shift1_and1_swapped:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %ESI<def> %ESI<kill> %RSI<def>
; CHECK-NEXT: # kill: %EDI<def> %EDI<kill> %RDI<def>
; CHECK-NEXT: andl $1, %esi
; CHECK-NEXT: leal (%rsi,%rdi,2), %eax
; CHECK-NEXT: retq
%shl = shl i32 %x, 1
%and = and i32 %y, 1
%or = or i32 %shl, %and
ret i32 %or
}
define i32 @or_shift2_and1(i32 %x, i32 %y) {
; CHECK-LABEL: or_shift2_and1:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %ESI<def> %ESI<kill> %RSI<def>
; CHECK-NEXT: # kill: %EDI<def> %EDI<kill> %RDI<def>
; CHECK-NEXT: andl $1, %esi
; CHECK-NEXT: leal (%rsi,%rdi,4), %eax
; CHECK-NEXT: retq
%shl = shl i32 %x, 2
%and = and i32 %y, 1
%or = or i32 %shl, %and
ret i32 %or
}
define i32 @or_shift3_and1(i32 %x, i32 %y) {
; CHECK-LABEL: or_shift3_and1:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %ESI<def> %ESI<kill> %RSI<def>
; CHECK-NEXT: # kill: %EDI<def> %EDI<kill> %RDI<def>
; CHECK-NEXT: andl $1, %esi
; CHECK-NEXT: leal (%rsi,%rdi,8), %eax
; CHECK-NEXT: retq
%shl = shl i32 %x, 3
%and = and i32 %y, 1
%or = or i32 %shl, %and
ret i32 %or
}
define i32 @or_shift3_and7(i32 %x, i32 %y) {
; CHECK-LABEL: or_shift3_and7:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %ESI<def> %ESI<kill> %RSI<def>
; CHECK-NEXT: # kill: %EDI<def> %EDI<kill> %RDI<def>
; CHECK-NEXT: andl $7, %esi
; CHECK-NEXT: leal (%rsi,%rdi,8), %eax
; CHECK-NEXT: retq
%shl = shl i32 %x, 3
%and = and i32 %y, 7
%or = or i32 %shl, %and
ret i32 %or
}
; The shift is too big for an LEA.
define i32 @or_shift4_and1(i32 %x, i32 %y) {
; CHECK-LABEL: or_shift4_and1:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %ESI<def> %ESI<kill> %RSI<def>
; CHECK-NEXT: # kill: %EDI<def> %EDI<kill> %RDI<def>
; CHECK-NEXT: shll $4, %edi
; CHECK-NEXT: andl $1, %esi
; CHECK-NEXT: leal (%rsi,%rdi), %eax
; CHECK-NEXT: retq
%shl = shl i32 %x, 4
%and = and i32 %y, 1
%or = or i32 %shl, %and
ret i32 %or
}
; The mask is too big for the shift, so the 'or' isn't equivalent to an 'add'.
define i32 @or_shift3_and8(i32 %x, i32 %y) {
; CHECK-LABEL: or_shift3_and8:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %EDI<def> %EDI<kill> %RDI<def>
; CHECK-NEXT: leal (,%rdi,8), %eax
; CHECK-NEXT: andl $8, %esi
; CHECK-NEXT: orl %esi, %eax
; CHECK-NEXT: retq
%shl = shl i32 %x, 3
%and = and i32 %y, 8
%or = or i32 %shl, %and
ret i32 %or
}
; 64-bit operands should work too.
define i64 @or_shift1_and1_64(i64 %x, i64 %y) {
; CHECK-LABEL: or_shift1_and1_64:
; CHECK: # BB#0:
; CHECK-NEXT: andl $1, %esi
; CHECK-NEXT: leaq (%rsi,%rdi,2), %rax
; CHECK-NEXT: retq
%shl = shl i64 %x, 1
%and = and i64 %y, 1
%or = or i64 %and, %shl
ret i64 %or
}