Subzero: Simplify the icmp i64 lowering.

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 714 matching lines @@
 
 if.then2:                                         ; preds = %if.end
   call void @func()
   br label %if.end3
 
 if.end3:                                          ; preds = %if.then2, %if.end
   ret void
 }
 ; CHECK-LABEL: icmpEq64
 ; CHECK: jne
-; CHECK: jne
+; CHECK: je
 ; CHECK: call
 ; CHECK: jne
-; CHECK: jne
+; CHECK: je
 ; CHECK: call
 ;
 ; OPTM1-LABEL: icmpEq64
 ; OPTM1: jne
-; OPTM1: jne
+; OPTM1: je
 ; OPTM1: call
 ; OPTM1: jne
-; OPTM1: jne
+; OPTM1: je
 ; OPTM1: call
 
 declare void @func()
 
 define internal void @icmpNe64(i64 %a, i64 %b, i64 %c, i64 %d) {
 entry:
   %cmp = icmp ne i64 %a, %b
   br i1 %cmp, label %if.then, label %if.end
 
 if.then:                                          ; preds = %entry
@@ skipping 188 matching lines @@
 ; OPTM1: call
 
 define internal i32 @icmpEq64Bool(i64 %a, i64 %b) {
 entry:
   %cmp = icmp eq i64 %a, %b
   %cmp.ret_ext = zext i1 %cmp to i32
   ret i32 %cmp.ret_ext
 }
 ; CHECK-LABEL: icmpEq64Bool
 ; CHECK: jne
-; CHECK: jne
+; CHECK: je
 ;
 ; OPTM1-LABEL: icmpEq64Bool
 ; OPTM1: jne
-; OPTM1: jne
+; OPTM1: je
 
 define internal i32 @icmpNe64Bool(i64 %a, i64 %b) {
 entry:
   %cmp = icmp ne i64 %a, %b
   %cmp.ret_ext = zext i1 %cmp to i32
   ret i32 %cmp.ret_ext
 }
 ; CHECK-LABEL: icmpNe64Bool
 ; CHECK: jne
 ; CHECK: jne
@@ skipping 325 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]+}},