Revamp long/ulong comparisons to use a much more efficient sequence (thanks

to Brian and the Sun compiler for pointing out that the obvious works :)

This also enables folding all long comparisons into setcc and branch
instructions: before we could only do == and !=

For example, for:
void test(unsigned long long A, unsigned long long B) {
   if (A < B) foo();
 }

We now generate:

test:
        subl $4, %esp
        movl %esi, (%esp)
        movl 8(%esp), %eax
        movl 12(%esp), %ecx
        movl 16(%esp), %edx
        movl 20(%esp), %esi
        subl %edx, %eax
        sbbl %esi, %ecx
        jae .LBBtest_2  # UnifiedReturnBlock
.LBBtest_1:     # then
        call foo
        movl (%esp), %esi
        addl $4, %esp
        ret
.LBBtest_2:     # UnifiedReturnBlock
        movl (%esp), %esi
        addl $4, %esp
        ret

Instead of:

test:
        subl $12, %esp
        movl %esi, 8(%esp)
        movl %ebx, 4(%esp)
        movl 16(%esp), %eax
        movl 20(%esp), %ecx
        movl 24(%esp), %edx
        movl 28(%esp), %esi
        cmpl %edx, %eax
        setb %al
        cmpl %esi, %ecx
        setb %bl
        cmove %ax, %bx
        testb %bl, %bl
        je .LBBtest_2   # UnifiedReturnBlock
.LBBtest_1:     # then
        call foo
        movl 4(%esp), %ebx
        movl 8(%esp), %esi
        addl $12, %esp
        ret
.LBBtest_2:     # UnifiedReturnBlock
        movl 4(%esp), %ebx
        movl 8(%esp), %esi
        addl $12, %esp
        ret


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18330 91177308-0d34-0410-b5e6-96231b3b80d8

0 files changed, 0 insertions, 0 deletions