maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/test/CodeGen/SystemZ/rot-01.ll

36 lines
733 B
LLVM
Raw Normal View History

[SystemZ] Use NILL instruction instead of NILF where possible Summary: SystemZ shift instructions only use the last 6 bits of the shift amount. When the result of an AND operation is used as a shift amount, this means that we can use the NILL instruction (which operates on the last 16 bits) rather than NILF (which operates on the last 32 bits) for a 16-bit savings in instruction size. Reviewers: uweigand Subscribers: llvm-commits Author: colpell Committing on behalf of Elliot. Differential Revision: http://reviews.llvm.org/D21686 llvm-svn: 274066
2016-06-29 05:03:19 +08:00
; Test shortening of NILL to NILF when the result is used as a rotate amount.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
; Test 32-bit rotate.
define i32 @f1(i32 %val, i32 %amt) {
; CHECK-LABEL: f1:
; CHECK: nill %r3, 31
; CHECK: rll %r2, %r2, 0(%r3)
%mod = urem i32 %amt, 32
%inv = sub i32 32, %mod
%parta = shl i32 %val, %mod
%partb = lshr i32 %val, %inv
%rotl = or i32 %parta, %partb
ret i32 %rotl
}
; Test 64-bit rotate.
define i64 @f2(i64 %val, i64 %amt) {
; CHECK-LABEL: f2:
[SystemZ] Remove AND mask of bottom 6 bits when result is used for shift/rotate On SystemZ, shift and rotate instructions only use the bottom 6 bits of the shift/rotate amount. Therefore, if the amount is ANDed with an immediate mask that has all of the bottom 6 bits set, we can remove the AND operation entirely. Differential Revision: http://reviews.llvm.org/D21854 llvm-svn: 274650
2016-07-07 02:13:11 +08:00
; CHECK: nill %r3, 31
[SystemZ] Use NILL instruction instead of NILF where possible Summary: SystemZ shift instructions only use the last 6 bits of the shift amount. When the result of an AND operation is used as a shift amount, this means that we can use the NILL instruction (which operates on the last 16 bits) rather than NILF (which operates on the last 32 bits) for a 16-bit savings in instruction size. Reviewers: uweigand Subscribers: llvm-commits Author: colpell Committing on behalf of Elliot. Differential Revision: http://reviews.llvm.org/D21686 llvm-svn: 274066
2016-06-29 05:03:19 +08:00
; CHECK: rllg %r2, %r2, 0(%r3)
[SystemZ] Remove AND mask of bottom 6 bits when result is used for shift/rotate On SystemZ, shift and rotate instructions only use the bottom 6 bits of the shift/rotate amount. Therefore, if the amount is ANDed with an immediate mask that has all of the bottom 6 bits set, we can remove the AND operation entirely. Differential Revision: http://reviews.llvm.org/D21854 llvm-svn: 274650
2016-07-07 02:13:11 +08:00
%mod = urem i64 %amt, 32
[SystemZ] Use NILL instruction instead of NILF where possible Summary: SystemZ shift instructions only use the last 6 bits of the shift amount. When the result of an AND operation is used as a shift amount, this means that we can use the NILL instruction (which operates on the last 16 bits) rather than NILF (which operates on the last 32 bits) for a 16-bit savings in instruction size. Reviewers: uweigand Subscribers: llvm-commits Author: colpell Committing on behalf of Elliot. Differential Revision: http://reviews.llvm.org/D21686 llvm-svn: 274066
2016-06-29 05:03:19 +08:00
%inv = sub i64 64, %mod
%parta = shl i64 %val, %mod
%partb = lshr i64 %val, %inv
%rotl = or i64 %parta, %partb
ret i64 %rotl
}