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The code pattern "imm0_255_neg" is used for checking if an immediate value is a small negative number.

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This patch changes the definition of negative from -0..-255 to -1..-255. I am changing this because of
a bug that we had in some of the patterns that assumed that "subs" of zero does not set the carry flag.

rdar://12028498



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167963 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem 2012-11-14 19:39:15 +00:00
parent 714a587115
commit 50b66387e3
2 changed files with 38 additions and 6 deletions
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13
lib/Target/ARM/ARMInstrThumb2.td
View File

@ -130,8 +130,9 @@ def imm0_4095_neg : Operand<i32>, PatLeaf<(i32 imm), [{
let ParserMatchClass = imm0_4095_neg_asmoperand;
}
def imm0_255_neg : PatLeaf<(i32 imm), [{
return (uint32_t)(-N->getZExtValue()) < 255;
def imm1_255_neg : PatLeaf<(i32 imm), [{
uint32_t Val = -N->getZExtValue();
return (Val > 0 && Val < 255);
}], imm_neg_XFORM>;
def imm0_255_not : PatLeaf<(i32 imm), [{
@ -1928,8 +1929,8 @@ defm t2RSBS : T2I_rbin_s_is <BinOpFrag<(ARMsubc node:$LHS, node:$RHS)>>;
// The AddedComplexity preferences the first variant over the others since
// it can be shrunk to a 16-bit wide encoding, while the others cannot.
let AddedComplexity = 1 in
def : T2Pat<(add GPR:$src, imm0_255_neg:$imm),
(t2SUBri GPR:$src, imm0_255_neg:$imm)>;
def : T2Pat<(add GPR:$src, imm1_255_neg:$imm),
(t2SUBri GPR:$src, imm1_255_neg:$imm)>;
def : T2Pat<(add GPR:$src, t2_so_imm_neg:$imm),
(t2SUBri GPR:$src, t2_so_imm_neg:$imm)>;
def : T2Pat<(add GPR:$src, imm0_4095_neg:$imm),
@ -1938,8 +1939,8 @@ def : T2Pat<(add GPR:$src, imm0_65535_neg:$imm),
(t2SUBrr GPR:$src, (t2MOVi16 (imm_neg_XFORM imm:$imm)))>;
let AddedComplexity = 1 in
def : T2Pat<(ARMaddc rGPR:$src, imm0_255_neg:$imm),
(t2SUBSri rGPR:$src, imm0_255_neg:$imm)>;
def : T2Pat<(ARMaddc rGPR:$src, imm1_255_neg:$imm),
(t2SUBSri rGPR:$src, imm1_255_neg:$imm)>;
def : T2Pat<(ARMaddc rGPR:$src, t2_so_imm_neg:$imm),
(t2SUBSri rGPR:$src, t2_so_imm_neg:$imm)>;
def : T2Pat<(ARMaddc rGPR:$src, imm0_65535_neg:$imm),

31
test/CodeGen/ARM/2012-11-14-subs_carry.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: llc < %s -mtriple=thumbv7-apple-ios | FileCheck %s
;CHECK: foo
;CHECK: adds
;CHECK-NEXT: adc
;CHECK-NEXT: bx
;rdar://12028498
define i32 @foo() nounwind ssp {
entry:
%tmp2 = zext i32 3 to i64
br label %bug_block
bug_block:
%tmp410 = and i64 1031, 1647010
%tmp411 = and i64 %tmp2, -211
%tmp412 = shl i64 %tmp410, %tmp2
%tmp413 = shl i64 %tmp411, %tmp2
%tmp415 = and i64 %tmp413, 1
%tmp420 = xor i64 0, %tmp415
%tmp421 = and i64 %tmp412, %tmp415
%tmp422 = shl i64 %tmp421, 1
br label %finish
finish:
%tmp423 = lshr i64 %tmp422, 32
%tmp424 = trunc i64 %tmp423 to i32
ret i32 %tmp424
}