[MC] Relax .fill size requirements
Avoid requirement that number of values must be known at assembler
time.
Fixes PR33586.
Reviewers: rnk, peter.smith, echristo, jyknight
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D46703
llvm-svn: 332741
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index a8a0177..bde838a 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -295,10 +295,13 @@
return cast<MCCompactEncodedInstFragment>(F).getContents().size();
case MCFragment::FT_Fill: {
auto &FF = cast<MCFillFragment>(F);
- int64_t Size = 0;
- if (!FF.getSize().evaluateAsAbsolute(Size, Layout))
+ int64_t NumValues = 0;
+ if (!FF.getNumValues().evaluateAsAbsolute(NumValues, Layout)) {
getContext().reportError(FF.getLoc(),
"expected assembly-time absolute expression");
+ return 0;
+ }
+ int64_t Size = NumValues * FF.getValueSize();
if (Size < 0) {
getContext().reportError(FF.getLoc(), "invalid number of bytes");
return 0;
@@ -557,19 +560,35 @@
case MCFragment::FT_Fill: {
++stats::EmittedFillFragments;
const MCFillFragment &FF = cast<MCFillFragment>(F);
- uint8_t V = FF.getValue();
+ uint64_t V = FF.getValue();
+ unsigned VSize = FF.getValueSize();
const unsigned MaxChunkSize = 16;
char Data[MaxChunkSize];
- memcpy(Data, &V, 1);
- for (unsigned I = 1; I < MaxChunkSize; ++I)
- Data[I] = Data[0];
+ // Duplicate V into Data as byte vector to reduce number of
+ // writes done. As such, do endian conversion here, not in OW.
+ const bool isLittleEndian = Asm.getContext().getAsmInfo()->isLittleEndian();
+ for (unsigned I = 0; I != VSize; ++I) {
+ unsigned index = isLittleEndian ? I : (VSize - I - 1);
+ Data[I] = uint8_t(V >> (index * 8));
+ }
+ for (unsigned I = VSize; I < MaxChunkSize; ++I)
+ Data[I] = Data[I - VSize];
- uint64_t Size = FragmentSize;
- for (unsigned ChunkSize = MaxChunkSize; ChunkSize; ChunkSize /= 2) {
- StringRef Ref(Data, ChunkSize);
- for (uint64_t I = 0, E = Size / ChunkSize; I != E; ++I)
- OW->writeBytes(Ref);
- Size = Size % ChunkSize;
+ // Set to largest multiple of VSize in Data.
+ const unsigned NumPerChunk = MaxChunkSize / VSize;
+ // Set ChunkSize to largest multiple of VSize in Data
+ const unsigned ChunkSize = VSize * NumPerChunk;
+
+ // Do copies by chunk.
+ StringRef Ref(Data, ChunkSize);
+ for (uint64_t I = 0, E = FragmentSize / ChunkSize; I != E; ++I)
+ OW->writeBytes(Ref);
+
+ // do remainder if needed.
+ unsigned TrailingCount = FragmentSize % ChunkSize;
+ if (TrailingCount) {
+ StringRef RefTail(Data, TrailingCount);
+ OW->writeBytes(RefTail);
}
break;
}