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[ARM] Skip inline asm memory operands in DAGToDAGISel 

Retry r275776 (no changes, we suspect the issue was with another commit).

The current logic for handling inline asm operands in DAGToDAGISel interprets
the operands by looking for constants, which should represent the flags
describing the kind of operand we're dealing with (immediate, memory, register
def etc). The operands representing actual data are skipped only if they are
non-const, with the exception of immediate operands which are skipped explicitly
when a flag describing an immediate is found.

The oversight is that memory operands may be const too (e.g. for device drivers
reading a fixed address), so we should explicitly skip the operand following a
flag describing a memory operand. If we don't, we risk interpreting that
constant as a flag, which is definitely not intended.

Fixes PR26038

Differential Revision: https://reviews.llvm.org/D22103

llvm-svn: 276101
This commit is contained in:
Diana Picus 2016-07-20 09:48:24 +00:00
parent 10f8472771
commit f345d40ae2
2 changed files with 22 additions and 0 deletions
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11
llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
View File

@ -4264,6 +4264,17 @@ bool ARMDAGToDAGISel::tryInlineAsm(SDNode *N){
if (Changed && InlineAsm::isUseOperandTiedToDef(Flag, DefIdx))
IsTiedToChangedOp = OpChanged[DefIdx];
// Memory operands to inline asm in the SelectionDAG are modeled with two
// operands: a constant of value InlineAsm::Kind_Mem followed by the input
// operand. If we get here and we have a Kind_Mem, skip the next operand (so
// it doesn't get misinterpreted), and continue. We do this here because
// it's important to update the OpChanged array correctly before moving on.
if (Kind == InlineAsm::Kind_Mem) {
SDValue op = N->getOperand(++i);
AsmNodeOperands.push_back(op);
continue;
}
if (Kind != InlineAsm::Kind_RegUse && Kind != InlineAsm::Kind_RegDef
&& Kind != InlineAsm::Kind_RegDefEarlyClobber)
continue;

11
llvm/test/CodeGen/ARM/inlineasm3.ll
View File

@ -121,3 +121,14 @@ entry:
%0 = tail call <4 x i32> asm "vld1.s32 {${0:e}[], ${0:f}[]}, [$1]", "=w,r"(i32* %p) nounwind
ret <4 x i32> %0
}
; Bugzilla PR26038
define i32 @fn1() local_unnamed_addr nounwind {
; CHECK-LABEL: fn1
entry:
; CHECK: mov [[addr:r[0-9]+]], #5
; CHECK: ldrh {{.*}}[[addr]]
%0 = tail call i32 asm "ldrh $0, $1", "=r,*Q"(i8* inttoptr (i32 5 to i8*)) nounwind
ret i32 %0
}