Subzero: Use cmov to improve lowering for the select instruction.

tests_lit/llvm2ice_tests/64bit.pnacl.ll

 ; This tries to be a comprehensive test of i64 operations, in
 ; particular the patterns for lowering i64 operations into constituent
 ; i32 operations on x86-32.
 
 ; RUN: %p2i --filetype=obj --disassemble -i %s --args -O2 \
 ; RUN:   | FileCheck %s
 ; RUN: %p2i --filetype=obj --disassemble -i %s --args -Om1 \
 ; RUN:   | FileCheck --check-prefix=OPTM1 %s
 
 @__init_array_start = internal constant [0 x i8] zeroinitializer, align 4
@@ skipping 1172 matching lines @@
   %cond = select i1 %cmp, i64 %a, i64 %b
   ret i64 %cond
 }
 ; CHECK-LABEL: select64VarVar
 ; CHECK: cmp
 ; CHECK: jb
 ; CHECK: ja
 ; CHECK: cmp
 ; CHECK: jb
 ; CHECK: cmp
-; CHECK: jne
+; CHECK: cmovne
 ;
 ; OPTM1-LABEL: select64VarVar
 ; OPTM1: cmp
 ; OPTM1: jb
 ; OPTM1: ja
 ; OPTM1: cmp
 ; OPTM1: jb
 ; OPTM1: cmp
-; OPTM1: jne
+; OPTM1: cmovne
 
 define internal i64 @select64VarConst(i64 %a, i64 %b) {
 entry:
   %cmp = icmp ult i64 %a, %b
   %cond = select i1 %cmp, i64 %a, i64 -2401053092306725256
   ret i64 %cond
 }
 ; CHECK-LABEL: select64VarConst
 ; CHECK: cmp
 ; CHECK: jb
 ; CHECK: ja
 ; CHECK: cmp
 ; CHECK: jb
 ; CHECK: cmp
-; CHECK: jne
+; CHECK: cmovne
 ;
 ; OPTM1-LABEL: select64VarConst
 ; OPTM1: cmp
 ; OPTM1: jb
 ; OPTM1: ja
 ; OPTM1: cmp
 ; OPTM1: jb
 ; OPTM1: cmp
-; OPTM1: jne
+; OPTM1: cmovne
 
 define internal i64 @select64ConstVar(i64 %a, i64 %b) {
 entry:
   %cmp = icmp ult i64 %a, %b
   %cond = select i1 %cmp, i64 -2401053092306725256, i64 %b
   ret i64 %cond
 }
 ; CHECK-LABEL: select64ConstVar
 ; CHECK: cmp
 ; CHECK: jb
 ; CHECK: ja
 ; CHECK: cmp
 ; CHECK: jb
 ; CHECK: cmp
-; CHECK: jne
+; CHECK: cmove
 ;
 ; OPTM1-LABEL: select64ConstVar
 ; OPTM1: cmp
 ; OPTM1: jb
 ; OPTM1: ja
 ; OPTM1: cmp
 ; OPTM1: jb
 ; OPTM1: cmp
-; OPTM1: jne
+; OPTM1: cmove
 
 define internal void @icmpEq64Imm() {
 entry:
   %cmp = icmp eq i64 123, 234
   br i1 %cmp, label %if.then, label %if.end
 
 if.then:                                          ; preds = %entry
   call void @func()
   br label %if.end
 
@@ skipping 34 matching lines @@
 
 if.end3:                                          ; preds = %if.then2, %if.end
   ret void
 }
 ; The following checks are not strictly necessary since one of the RUN
 ; lines actually runs the output through the assembler.
 ; CHECK-LABEL: icmpLt64Imm
 ; CHECK-NOT: cmp 0x{{[0-9a-f]+}},
 ; OPTM1-LABEL: icmpLt64Imm
 ; OPTM1-NOT: cmp 0x{{[0-9a-f]+}},