llvm/lib
Chris Lattner 0ea26ca45b Expand 64-bit shifts more optimally if we know that the high bit of the
shift amount is one or zero.  For example, for:

long long foo1(long long X, int C) {
  return X << (C|32);
}

long long foo2(long long X, int C) {
  return X << (C&~32);
}

we get:

_foo1:
        movb $31, %cl
        movl 4(%esp), %edx
        andb 12(%esp), %cl
        shll %cl, %edx
        xorl %eax, %eax
        ret
_foo2:
        movb $223, %cl
        movl 4(%esp), %eax
        movl 8(%esp), %edx
        andb 12(%esp), %cl
        shldl %cl, %eax, %edx
        shll %cl, %eax
        ret

instead of:

_foo1:
        subl $4, %esp
        movl %ebx, (%esp)
        movb $32, %bl
        movl 8(%esp), %eax
        movl 12(%esp), %edx
        movb %bl, %cl
        orb 16(%esp), %cl
        shldl %cl, %eax, %edx
        shll %cl, %eax
        xorl %ecx, %ecx
        testb %bl, %bl
        cmovne %eax, %edx
        cmovne %ecx, %eax
        movl (%esp), %ebx
        addl $4, %esp
        ret
_foo2:
        subl $4, %esp
        movl %ebx, (%esp)
        movb $223, %cl
        movl 8(%esp), %eax
        movl 12(%esp), %edx
        andb 16(%esp), %cl
        shldl %cl, %eax, %edx
        shll %cl, %eax
        xorl %ecx, %ecx
        xorb %bl, %bl
        testb %bl, %bl
        cmovne %eax, %edx
        cmovne %ecx, %eax
        movl (%esp), %ebx
        addl $4, %esp
        ret


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30506 91177308-0d34-0410-b5e6-96231b3b80d8
2006-09-20 03:38:48 +00:00
..
Analysis Explain change with a comment. 2006-09-17 17:51:00 +00:00
Archive For PR797: 2006-08-25 19:54:53 +00:00
AsmParser Added some eye-candy for Subtarget type checking 2006-09-17 20:25:45 +00:00
Bytecode Small fixes for supporting dll* linkage types 2006-09-17 13:06:18 +00:00
CodeGen Expand 64-bit shifts more optimally if we know that the high bit of the 2006-09-20 03:38:48 +00:00
Debugger For PR797: 2006-08-25 17:43:11 +00:00
ExecutionEngine Unbreak the JIT 2006-09-15 04:56:11 +00:00
Linker Adding dllimport, dllexport and external weak linkage types. 2006-09-14 18:23:27 +00:00
Support Instantiate Statistic<> in one place, not in every .o file that uses it. 2006-08-30 04:17:00 +00:00
System Use new config.h macro 2006-09-14 06:21:59 +00:00
Target fix header 2006-09-19 16:41:40 +00:00
Transforms Back out Chris' last set of changes. This breaks 177.mesa and povray somehow. 2006-09-20 01:39:40 +00:00
VMCore add a helper method 2006-09-18 04:54:57 +00:00
Makefile