In asm's, output operands with matching input constraints
have to be registers, per gcc documentation. This affects
the logic for determining what "g" should lower to. PR 7393.
A couple of existing testcases are affected.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107079 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 8019116..2db55d3 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2547,12 +2547,12 @@
unsigned BestIdx = 0;
TargetLowering::ConstraintType BestType = TargetLowering::C_Unknown;
int BestGenerality = -1;
-
+
// Loop over the options, keeping track of the most general one.
for (unsigned i = 0, e = OpInfo.Codes.size(); i != e; ++i) {
TargetLowering::ConstraintType CType =
TLI.getConstraintType(OpInfo.Codes[i]);
-
+
// If this is an 'other' constraint, see if the operand is valid for it.
// For example, on X86 we might have an 'rI' constraint. If the operand
// is an integer in the range [0..31] we want to use I (saving a load
@@ -2570,6 +2570,11 @@
}
}
+ // Things with matching constraints can only be registers, per gcc
+ // documentation. This mainly affects "g" constraints.
+ if (CType == TargetLowering::C_Memory && OpInfo.hasMatchingInput())
+ continue;
+
// This constraint letter is more general than the previous one, use it.
int Generality = getConstraintGenerality(CType);
if (Generality > BestGenerality) {