/// <summary>
/// Inserts the statement <paramref name="ass"/> after the statement
/// <paramref name="stmBefore"/>, skipping any AliasAssignments that
/// statements that may have been added after
/// <paramref name="stmBefore"/>.
/// </summary>
/// <param name="stmBefore"></param>
/// <param name="ass"></param>
/// <returns></returns>
public SsaIdentifier InsertAfterDefinition(Statement stmBefore, AliasAssignment ass)
{
var b = stmBefore.Block;
int i = b.Statements.IndexOf(stmBefore);
// Skip alias statements
while (i < b.Statements.Count - 1 && b.Statements[i + 1].Instruction is AliasAssignment)
{
++i;
}
var stm = new Statement(stmBefore.LinearAddress, ass, stmBefore.Block);
stmBefore.Block.Statements.Insert(i + 1, stm);
var sidTo = ssaIds.Add(ass.Dst, stm, ass.Src, false);
ass.Dst = sidTo.Identifier;
return(sidTo);
}
public override SsaIdentifier ReadBlockLocalVariable(SsaBlockState bs)
{
DebugEx.Verbose(trace, " ReadBlockLocalVariable: ({0}, {1}, ({2})", bs.Block.Name, id, this.liveBits);
if (!bs.currentDef.TryGetValue(id.Storage.Domain, out var alias))
{
return(null);
}
// Identifier id is defined locally in this block.
// Has an exact alias already been calculated?
if (alias.ExactAliases.TryGetValue(id.Storage, out var sid))
{
DebugEx.Verbose(trace, " found alias ({0}, {1})", bs.Block.Name, sid.Identifier.Name);
return(sid);
}
// At least some of the bits of 'id' are defined locally in this
// block. Walk across the bits of 'id', collecting all parts
// defined into a sequence.
int offsetLo = this.liveBits.Lsb;
int offsetHi = this.liveBits.Msb;
var sids = new List <(SsaIdentifier, BitRange)>();
while (offsetLo < offsetHi)
{
var useRange = new BitRange(offsetLo, offsetHi);
var(sidElem, usedRange, defRange) = FindIntersectingRegister(alias.Definitions, useRange);
if (sidElem == null || offsetLo < usedRange.Lsb)
{
// Found a gap in the register that wasn't defined in
// this basic block. Seek backwards
var bitrangeR = sidElem == null
? useRange
: new BitRange(offsetLo, usedRange.Lsb);
var idR = MakeTmpIdentifier(sidElem, bitrangeR);
var rx = new RegisterTransformer(idR, stm, this.outer)
{
liveBits = bitrangeR
};
var sidR = rx.ReadVariableRecursive(bs);
sids.Add((sidR, bitrangeR));
offsetLo = bitrangeR.Msb;
}
if (sidElem != null)
{
sids.Add((sidElem, defRange));
offsetLo = usedRange.Msb;
}
}
if (sids.Count == 1)
{
var sidSlice = MakeSlice(sids[0].Item1, sids[0].Item2, this.id);
alias.ExactAliases[this.id.Storage] = sidSlice;
return(sidSlice);
}
else
{
sids.Reverse(); // Order sids in big-endian order
var elems = new List <Expression>();
foreach (var(sidElem, bitrange) in sids)
{
var idSlice = MakeTmpIdentifier(sidElem, bitrange);
var sidSlice = MakeSlice(sidElem, bitrange, idSlice);
alias.ExactAliases[sidSlice.OriginalIdentifier.Storage] = sidSlice;
elems.Add(sidSlice.Identifier);
}
var seq = outer.m.Seq(elems.ToArray());
var assSeq = new AliasAssignment(id, seq);
var sidTo = InsertBeforeStatement(bs.Block, this.stm, assSeq);
seq.Accept(new InstructionUseAdder(sidTo.DefStatement, ssaIds));
alias.ExactAliases[this.id.Storage] = sidTo;
return(sidTo);
}
}
