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Compile x86-64-and-mask.ll into:

Browse Source 
_test:
	movl	%edi, %eax
	ret

instead of:

_test:
        movl    $4294967295, %ecx
        movq    %rdi, %rax
        andq    %rcx, %rax
        ret

It would be great to write this as a Pat pattern that used subregs 
instead of a 'pseudo' instruction, but I don't know how to do that
in td files.

llvm-svn: 47658
This commit is contained in:
Chris Lattner 2008-02-27 05:47:54 +00:00
parent 7553230e3a
commit bc686e546a
3 changed files with 26 additions and 10 deletions
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11
lib/Target/X86/README-X86-64.txt
View File

@ -249,15 +249,6 @@ _a:
addq $8, %rsp
ret
note the dead rsp adjustments. Also, there is surely a better/shorter way
to clear the top 32-bits of a 64-bit register than movl+andq. Testcase here:
unsigned long long c(unsigned long long a) {return a&4294967295; }
_c:
movl $4294967295, %ecx
movq %rdi, %rax
andq %rcx, %rax
ret
note the dead rsp adjustments.
//===---------------------------------------------------------------------===//

13
lib/Target/X86/X86Instr64bit.td
View File

@ -61,6 +61,13 @@ def i64immSExt8 : PatLeaf<(i64 imm), [{
return (int64_t)N->getValue() == (int8_t)N->getValue();
}]>;
def i64immFFFFFFFF : PatLeaf<(i64 imm), [{
// i64immFFFFFFFF - True if this is a specific constant we can't write in
// tblgen files.
return N->getValue() == 0x00000000FFFFFFFFULL;
}]>;
def sextloadi64i8 : PatFrag<(ops node:$ptr), (i64 (sextloadi8 node:$ptr))>;
def sextloadi64i16 : PatFrag<(ops node:$ptr), (i64 (sextloadi16 node:$ptr))>;
def sextloadi64i32 : PatFrag<(ops node:$ptr), (i64 (sextloadi32 node:$ptr))>;
@ -1091,6 +1098,12 @@ def PsMOVZX64rm32: I<0x8B, MRMSrcMem, (outs GR64:$dst), (ins i32mem:$src),
"mov{l}\t{$src, ${dst:subreg32}|${dst:subreg32}, $src}",
[(set GR64:$dst, (zextloadi64i32 addr:$src))]>;
/// PsAND64rrFFFFFFFF - r = r & (2^32-1)
def PsAND64rrFFFFFFFF
: I<0x89, MRMDestReg, (outs GR64:$dst), (ins GR64:$src),
"mov{l}\t{${src:subreg32}, ${dst:subreg32}|${dst:subreg32}, ${src:subreg32}}",
[(set GR64:$dst, (and GR64:$src, i64immFFFFFFFF))]>;
// Alias instructions that map movr0 to xor. Use xorl instead of xorq; it's
// equivalent due to implicit zero-extending, and it sometimes has a smaller

12
test/CodeGen/X86/x86-64-and-mask.ll Normal file
View File

@ -0,0 +1,12 @@
; RUN: llvm-as < %s | llc | grep {movl.*%edi, %eax}
; This should be a single mov, not a load of immediate + andq.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
target triple = "x86_64-apple-darwin8"
define i64 @test(i64 %x) nounwind {
entry:
%tmp123 = and i64 %x, 4294967295 ; <i64> [#uses=1]
ret i64 %tmp123
}