Subzero: Use a setcc sequence for better icmp lowering.

tests_lit/assembler/x86/sandboxing.ll

 ; Tests basics and corner cases of x86-32 sandboxing, using -Om1 in
 ; the hope that the output will remain stable.  When packing bundles,
 ; we try to limit to a few instructions with well known sizes and
 ; minimal use of registers and stack slots in the lowering sequence.
 
 ; RUN: %p2i -i %s --filetype=obj --disassemble --args -Om1 \
 ; RUN:   -ffunction-sections -sandbox | FileCheck %s
 
 declare void @call_target()
 @global_byte = internal global [1 x i8] zeroinitializer
@@ skipping 78 matching lines @@
 ; CHECK-NEXT: 20: {{.*}} mov WORD PTR
 ; CHECK-NEXT: 29: {{.*}} mov WORD PTR
 ; CHECK-NEXT: 32: {{.*}} mov WORD PTR
 ; CHECK-NEXT: 3b: {{.*}} nop
 ; CHECK: 40: {{.*}} mov WORD PTR
 
 ; A zero-byte instruction (e.g. local label definition) at a bundle
 ; boundary should not trigger nop padding.
 define void @label_at_boundary(i32 %arg) {
 entry:
+  %cmp = icmp eq i32 %arg, 0               ; Create a var to select on below.
   call void @call_target()
   ; bundle boundary
   %addr_short = bitcast [2 x i8]* @global_short to i16*
   store i16 0, i16* %addr_short, align 1   ; 9-byte instruction
-  %cmp = icmp eq i32 %arg, 0               ; 23-byte lowering sequence
+  %dummy = select i1 %cmp, i32 3, i32 5    ; 23-byte lowering sequence
   ; label is here
   store i16 0, i16* %addr_short, align 1   ; 9-byte instruction
   ret void
 }
 ; CHECK-LABEL: label_at_boundary
 ; CHECK: call
-; We rely on the hideous 4-instruction 23-byte Om1 lowering sequence for icmp.
+; We rely on the hideous 4-instruction 23-byte Om1 lowering sequence for select.
 ; CHECK-NEXT: 20: {{.*}} mov WORD PTR
-; CHECK-NEXT: 29: {{.*}} cmp DWORD PTR
+; CHECK-NEXT: 29: {{.*}} cmp BYTE PTR
 ; CHECK-NEXT: 2e: {{.*}} mov DWORD PTR
-; CHECK-NEXT: 36: {{.*}} je 40
+; CHECK-NEXT: 36: {{.*}} jne 40
 ; CHECK-NEXT: 38: {{.*}} mov DWORD PTR
 ; CHECK-NEXT: 40: {{.*}} mov WORD PTR
 
 ; Bundle lock without padding.
 define void @bundle_lock_without_padding() {
 entry:
   %addr_short = bitcast [2 x i8]* @global_short to i16*
   store i16 0, i16* %addr_short, align 1   ; 9-byte instruction
   ret void
 }
@@ skipping 118 matching lines @@
   ret void
 }
 ; CHECK-LABEL: checkpoint_restore_stack_adjustment
 ; CHECK: call
 ; CHECK: sub esp,0x10
 ; The address of %arg should be [esp+0x20], not [esp+0x30].
 ; CHECK-NEXT: mov [[REG:.*]],DWORD PTR [esp+0x20]
 ; CHECK-NEXT: mov DWORD PTR [esp],[[REG]]
 ; CHECK: call
 ; CHECK: add esp,0x10