These tests all follow the same pattern:
mov r2, r0
movs r0, #0
$CMP r2, r1
it eq
moveq r0, #1
bx lr
The first 'mov' can be eliminated by rematerializing 'movs r0, #0' below the
test instruction:
$CMP r0, r1
mov.w r0, #0
it eq
moveq r0, #1
bx lr
So far, only physreg coalescing can do that. The register allocators won't yet
split live ranges just to eliminate copies. They can learn, but this particular
problem is not likely to show up in real code. It only appears because r0 is
used for both the function argument and return value.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130858
91177308-0d34-0410-b5e6-
96231b3b80d8
-; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
+; RUN: llc < %s -march=thumb -mattr=+thumb2 -join-physregs | FileCheck %s
+
+; These tests implicitly depend on 'movs r0, #0' being rematerialized below the
+; test as 'mov.w r0, #0'. So far, that requires physreg joining.
define i1 @f1(i32 %a, i32 %b) {
%nb = sub i32 0, %b
-; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
+; RUN: llc < %s -march=thumb -mattr=+thumb2 -join-physregs | FileCheck %s
+
+; These tests implicitly depend on 'movs r0, #0' being rematerialized below the
+; test as 'mov.w r0, #0'. So far, that requires physreg joining.
; 0x000000bb = 187
define i1 @f1(i32 %a) {
-; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
+; RUN: llc < %s -march=thumb -mattr=+thumb2 -join-physregs | FileCheck %s
+
+; These tests implicitly depend on 'movs r0, #0' being rematerialized below the
+; test as 'mov.w r0, #0'. So far, that requires physreg joining.
define i1 @f1(i32 %a, i32 %b) {
; CHECK: f1:
-; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
+; RUN: llc < %s -march=thumb -mattr=+thumb2 -join-physregs | FileCheck %s
+; These tests implicitly depend on 'movs r0, #0' being rematerialized below the
+; test as 'mov.w r0, #0'. So far, that requires physreg joining.
; 0x000000bb = 187
define i1 @f1(i32 %a) {
-; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
+; RUN: llc < %s -march=thumb -mattr=+thumb2 -join-physregs | FileCheck %s
+
+; These tests implicitly depend on 'movs r0, #0' being rematerialized below the
+; tst as 'mov.w r0, #0'. So far, that requires physreg joining.
define i1 @f1(i32 %a, i32 %b) {
; CHECK: f1
-; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
+; RUN: llc < %s -march=thumb -mattr=+thumb2 -join-physregs | FileCheck %s
+; These tests implicitly depend on 'movs r0, #0' being rematerialized below the
+; tst as 'mov.w r0, #0'. So far, that requires physreg joining.
; 0x000000bb = 187
define i1 @f1(i32 %a) {
-; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
+; RUN: llc < %s -march=thumb -mattr=+thumb2 -join-physregs | FileCheck %s
+
+; These tests implicitly depend on 'movs r0, #0' being rematerialized below the
+; tst as 'mov.w r0, #0'. So far, that requires physreg joining.
define i1 @f1(i32 %a, i32 %b) {
; CHECK: f1: