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Teach Thumb2 isel to fold and->rotr ==> ROR.

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Generalization of Nate Begeman's patch!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130502 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-04-29 14:18:15 +00:00
parent a432997745
commit d49ffe8284
2 changed files with 13 additions and 2 deletions
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9
lib/Target/ARM/ARMInstrThumb2.td
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@ -84,6 +84,11 @@ def imm0_255_not : PatLeaf<(i32 imm), [{
return (uint32_t)(~N->getZExtValue()) < 255;
}], imm_comp_XFORM>;
def lo5AllOne : PatLeaf<(i32 imm), [{
// Returns true if all low 5-bits are 1.
return (((uint32_t)N->getZExtValue()) & 0x1FUL) == 0x1FUL;
}]>;
// Define Thumb2 specific addressing modes.
// t2addrmode_imm12 := reg + imm12
@ -2023,6 +2028,10 @@ defm t2LSR : T2I_sh_ir<0b01, "lsr", BinOpFrag<(srl node:$LHS, node:$RHS)>>;
defm t2ASR : T2I_sh_ir<0b10, "asr", BinOpFrag<(sra node:$LHS, node:$RHS)>>;
defm t2ROR : T2I_sh_ir<0b11, "ror", BinOpFrag<(rotr node:$LHS, node:$RHS)>>;
// (rotr x, (and y, 0x...1f)) ==> (ROR x, y)
def : Pat<(rotr rGPR:$lhs, (and rGPR:$rhs, lo5AllOne)),
(t2RORrr rGPR:$lhs, rGPR:$rhs)>;
let Uses = [CPSR] in {
def t2RRX : T2sTwoReg<(outs rGPR:$Rd), (ins rGPR:$Rm), IIC_iMOVsi,
"rrx", "\t$Rd, $Rm",

6
test/CodeGen/Thumb2/thumb2-ror.ll
View File

@ -11,11 +11,13 @@ define i32 @f1(i32 %a) {
}
; CHECK: f2:
; CHECK-NOT: and
; CHECK: ror
define i32 @f2(i32 %v, i32 %nbits) {
entry:
%shr = lshr i32 %v, %nbits
%sub = sub i32 32, %nbits
%and = and i32 %nbits, 31
%shr = lshr i32 %v, %and
%sub = sub i32 32, %and
%shl = shl i32 %v, %sub
%or = or i32 %shl, %shr
ret i32 %or