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Don't use an array when a simple shift/bit scan will do #79493

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2 changes: 2 additions & 0 deletions src/coreclr/jit/emit.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2388,6 +2388,7 @@ void emitter::emitSetFrameRangeArgs(int offsLo, int offsHi)
* small encoding (0 through 3), and vice versa.
*/

#if DEBUG
const emitter::opSize emitter::emitSizeEncode[] = {
emitter::OPSZ1, emitter::OPSZ2, OPSIZE_INVALID, emitter::OPSZ4, OPSIZE_INVALID, OPSIZE_INVALID, OPSIZE_INVALID,
emitter::OPSZ8, OPSIZE_INVALID, OPSIZE_INVALID, OPSIZE_INVALID, OPSIZE_INVALID, OPSIZE_INVALID, OPSIZE_INVALID,
Expand All @@ -2398,6 +2399,7 @@ const emitter::opSize emitter::emitSizeEncode[] = {

const emitAttr emitter::emitSizeDecode[emitter::OPSZ_COUNT] = {EA_1BYTE, EA_2BYTE, EA_4BYTE,
EA_8BYTE, EA_16BYTE, EA_32BYTE};
#endif

/*****************************************************************************
*
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14 changes: 10 additions & 4 deletions src/coreclr/jit/emit.h
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Expand Up @@ -488,8 +488,10 @@ class emitter

#define OPSIZE_INVALID ((opSize)0xffff)

#if DEBUG
static const emitter::opSize emitSizeEncode[];
static const emitAttr emitSizeDecode[];
#endif

static emitter::opSize emitEncodeSize(emitAttr size);
static emitAttr emitDecodeSize(emitter::opSize ensz);
Expand Down Expand Up @@ -1047,7 +1049,7 @@ class emitter
}
#endif // TARGET_LOONGARCH64

emitAttr idOpSize()
emitAttr idOpSize() const
{
return emitDecodeSize(_idOpSize);
}
Expand Down Expand Up @@ -2856,15 +2858,19 @@ inline emitAttr emitActualTypeSize(T type)
{
assert(size == EA_1BYTE || size == EA_2BYTE || size == EA_4BYTE || size == EA_8BYTE || size == EA_16BYTE ||
size == EA_32BYTE);
emitter::opSize result = static_cast<emitter::opSize>(genLog2(static_cast<uint32_t>(size)));

return emitSizeEncode[((int)size) - 1];
assert(result == emitSizeEncode[static_cast<uint32_t>(size) - 1]);
return result;
}

/* static */ inline emitAttr emitter::emitDecodeSize(emitter::opSize ensz)
{
assert(((unsigned)ensz) < OPSZ_COUNT);
assert(static_cast<uint32_t>(ensz) < OPSZ_COUNT);
emitAttr result = static_cast<emitAttr>(1 << static_cast<uint32_t>(ensz));

return emitSizeDecode[ensz];
assert(result == emitSizeDecode[ensz]);
return result;
}

/*****************************************************************************
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8 changes: 6 additions & 2 deletions src/coreclr/jit/emitxarch.h
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Expand Up @@ -705,15 +705,19 @@ void emitAdjustStackDepth(instruction ins, ssize_t val);
inline emitter::opSize emitEncodeScale(size_t scale)
{
assert(scale == 1 || scale == 2 || scale == 4 || scale == 8);
emitter::opSize result = static_cast<emitter::opSize>(genLog2(static_cast<uint32_t>(scale)));

return emitSizeEncode[scale - 1];
assert(result == emitSizeEncode[scale - 1]);
return result;
}

inline emitAttr emitDecodeScale(unsigned ensz)
{
assert(ensz < 4);
emitAttr result = static_cast<emitAttr>(1 << ensz);

return emitter::emitSizeDecode[ensz];
assert(result == emitter::emitSizeDecode[ensz]);
return result;
}

/************************************************************************/
Expand Down