Subzero: Use the linear-scan register allocator for Om1 as well.

tests_lit/llvm2ice_tests/nop-insertion.ll

 ; This is a smoke test of nop insertion.
 
 ; Don't use integrated-as because this currently depends on the # variant
 ; assembler comment.
 ; RUN: %p2i -i %s -a -rng-seed=1 -nop-insertion -nop-insertion-percentage=50 \
 ; RUN:    -max-nops-per-instruction=1 -integrated-as=false \
 ; RUN:    | FileCheck %s --check-prefix=PROB50
 ; RUN: %p2i -i %s -a -rng-seed=1 -nop-insertion -nop-insertion-percentage=90 \
 ; RUN:    -max-nops-per-instruction=1 -integrated-as=false \
 ; RUN:    | FileCheck %s --check-prefix=PROB90
@@ skipping 13 matching lines @@
 ; PROB50: movups %xmm1, 16(%esp)
 ; PROB50: nop # variant = 0
 ; PROB50: movups 32(%esp), %xmm0
 ; PROB50: nop # variant = 4
 ; PROB50: pshufd $49, 32(%esp), %xmm1
 ; PROB50: pshufd $49, 16(%esp), %xmm2
 ; PROB50: pmuludq 16(%esp), %xmm0
 ; PROB50: pmuludq %xmm2, %xmm1
 ; PROB50: nop # variant = 0
 ; PROB50: shufps $136, %xmm1, %xmm0
-; PROB50: pshufd $216, %xmm0, %xmm1
+; PROB50: pshufd $216, %xmm0, %xmm0
 ; PROB50: nop # variant = 2
-; PROB50: movups %xmm1, (%esp)
+; PROB50: movups %xmm0, (%esp)
 ; PROB50: movups (%esp), %xmm0
 ; PROB50: addl $60, %esp
 ; PROB50: nop # variant = 0
 ; PROB50: ret
 
 ; PROB90-LABEL: mul_v4i32:
 ; PROB90: nop # variant = 3
 ; PROB90: subl $60, %esp
 ; PROB90: nop # variant = 4
 ; PROB90: movups %xmm0, 32(%esp)
 ; PROB90: nop # variant = 3
 ; PROB90: movups %xmm1, 16(%esp)
 ; PROB90: nop # variant = 2
 ; PROB90: movups 32(%esp), %xmm0
 ; PROB90: nop # variant = 3
 ; PROB90: pshufd $49, 32(%esp), %xmm1
 ; PROB90: nop # variant = 4
 ; PROB90: pshufd $49, 16(%esp), %xmm2
 ; PROB90: nop # variant = 0
 ; PROB90: pmuludq 16(%esp), %xmm0
 ; PROB90: nop # variant = 2
 ; PROB90: pmuludq %xmm2, %xmm1
 ; PROB90: nop # variant = 3
 ; PROB90: shufps $136, %xmm1, %xmm0
 ; PROB90: nop # variant = 4
-; PROB90: pshufd $216, %xmm0, %xmm1
+; PROB90: pshufd $216, %xmm0, %xmm0
 ; PROB90: nop # variant = 2
-; PROB90: movups %xmm1, (%esp)
+; PROB90: movups %xmm0, (%esp)
 ; PROB90: nop # variant = 4
 ; PROB90: movups (%esp), %xmm0
 ; PROB90: nop # variant = 2
 ; PROB90: addl $60, %esp
 ; PROB90: nop # variant = 3
 ; PROB90: ret
 
 ; MAXNOPS2-LABEL: mul_v4i32:
 ; MAXNOPS2: subl $60, %esp
 ; MAXNOPS2: nop # variant = 4
 ; MAXNOPS2: movups %xmm0, 32(%esp)
 ; MAXNOPS2: nop # variant = 0
 ; MAXNOPS2: nop # variant = 4
 ; MAXNOPS2: movups %xmm1, 16(%esp)
 ; MAXNOPS2: movups 32(%esp), %xmm0
 ; MAXNOPS2: nop # variant = 0
 ; MAXNOPS2: pshufd $49, 32(%esp), %xmm1
 ; MAXNOPS2: nop # variant = 2
 ; MAXNOPS2: pshufd $49, 16(%esp), %xmm2
 ; MAXNOPS2: pmuludq 16(%esp), %xmm0
 ; MAXNOPS2: nop # variant = 0
 ; MAXNOPS2: nop # variant = 3
 ; MAXNOPS2: pmuludq %xmm2, %xmm1
 ; MAXNOPS2: shufps $136, %xmm1, %xmm0
-; MAXNOPS2: pshufd $216, %xmm0, %xmm1
+; MAXNOPS2: pshufd $216, %xmm0, %xmm0
 ; MAXNOPS2: nop # variant = 3
-; MAXNOPS2: movups %xmm1, (%esp)
+; MAXNOPS2: movups %xmm0, (%esp)
 ; MAXNOPS2: nop # variant = 0
 ; MAXNOPS2: movups (%esp), %xmm0
 ; MAXNOPS2: nop # variant = 2
 ; MAXNOPS2: addl $60, %esp
 ; MAXNOPS2: nop # variant = 4
 ; MAXNOPS2: ret
 }