The following program assembles with llvm-as:

  define i32 @test1(i32 %a, i32 %b) {
  entry:
          icmp eq i32 %b, %a              ; <i1>:0 [#uses=1]
          zext i1 %0 to i32               ; <i32>:0 [#uses=1]
          ret i32 %0
  }

The type of %0 is simultaneously i1 and i32. By contrast, naming the variable %A
makes it invalid. This does not assemble

  define i32 @test2(i32 %a, i32 %b) {
  entry:
          %A = icmp eq i32 %b, %a
          %A = zext i1 %A to i32
          ret i32 %A
  }

with the error "Redefinition of value 'A' of type 'i32'" which is desired. I'd
like this C code:

  int test1(int a, int b) { return a == b; }

to produce this llvm assembly:

  define i32 @test1(i32 %a, i32 %b) {
  entry:
          icmp eq i32 %b, %a              ; <i1>:0 [#uses=1]
          zext i1 %1 to i32               ; <i32>:1 [#uses=1]
          ret i32 %1
  }