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llvm-mirror/test/CodeGen/SystemZ/rot-shift-64-sub-amt.ll
Jonas Paulsson dc069b2d6c [SystemZ] Improve instruction selection of 64 bit shifts and rotates.
For shift and rotate instructions that only use the last 6 bits of the shift
amount, a shift amount of (x*64-s) can be substituted with (-s). This saves
one instruction and a register:

  lhi     %r1, 64
  sr      %r1, %r3
  sllg    %r2, %r2, 0(%r1)
  =>
  lcr     %r1, %r3
  sllg    %r2, %r2, 0(%r1)

Review: Ulrich Weigand
llvm-svn: 357481
2019-04-02 15:36:30 +00:00

83 lines
1.8 KiB
LLVM

; Test that the case of (64 - shift) used by a shift/rotate instruction is
; implemented with an lcr. This should also work for any multiple of 64.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 | FileCheck %s
define i64 @f1(i64 %in, i64 %sh) {
; CHECK-LABEL: f1:
; CHECK: lcr %r1, %r3
; CHECK: sllg %r2, %r2, 0(%r1)
%sub = sub i64 64, %sh
%shl = shl i64 %in, %sub
ret i64 %shl
}
define i64 @f2(i64 %in, i64 %sh) {
; CHECK-LABEL: f2:
; CHECK: lcr %r1, %r3
; CHECK: srag %r2, %r2, 0(%r1)
%sub = sub i64 64, %sh
%shl = ashr i64 %in, %sub
ret i64 %shl
}
define i64 @f3(i64 %in, i64 %sh) {
; CHECK-LABEL: f3:
; CHECK: lcr %r1, %r3
; CHECK: srlg %r2, %r2, 0(%r1)
%sub = sub i64 64, %sh
%shl = lshr i64 %in, %sub
ret i64 %shl
}
define i64 @f4(i64 %in, i64 %sh) {
; CHECK-LABEL: f4:
; CHECK: lcr %r1, %r3
; CHECK: rllg %r2, %r2, 0(%r1)
%shr = lshr i64 %in, %sh
%sub = sub i64 64, %sh
%shl = shl i64 %in, %sub
%or = or i64 %shl, %shr
ret i64 %or
}
define i64 @f5(i64 %in, i64 %sh) {
; CHECK-LABEL: f5:
; CHECK: lcr %r1, %r3
; CHECK: sllg %r2, %r2, 0(%r1)
%sub = sub i64 128, %sh
%shl = shl i64 %in, %sub
ret i64 %shl
}
define i64 @f6(i64 %in, i64 %sh) {
; CHECK-LABEL: f6:
; CHECK: lcr %r1, %r3
; CHECK: srag %r2, %r2, 0(%r1)
%sub = sub i64 256, %sh
%shl = ashr i64 %in, %sub
ret i64 %shl
}
define i64 @f7(i64 %in, i64 %sh) {
; CHECK-LABEL: f7:
; CHECK: lcr %r1, %r3
; CHECK: srlg %r2, %r2, 0(%r1)
%sub = sub i64 512, %sh
%shl = lshr i64 %in, %sub
ret i64 %shl
}
define i64 @f8(i64 %in, i64 %sh) {
; CHECK-LABEL: f8:
; CHECK: lcr %r1, %r3
; CHECK: srlg %r0, %r2, 0(%r3)
; CHECK: sllg %r2, %r2, 0(%r1)
; CHECK: ogr %r2, %r0
%shr = lshr i64 %in, %sh
%sub = sub i64 1024, %sh
%shl = shl i64 %in, %sub
%or = or i64 %shl, %shr
ret i64 %or
}