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[RISC-V] On Stack Replacement #2

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Merged
sirntar merged 6 commits into from
Dec 18, 2023
Merged

[RISC-V] On Stack Replacement #2

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71844c6
[RISC-V] Implement On Stack Replacement
sirntar Dec 7, 2023
377e6f4
[RISC-V] Sketch implementation of genAllocLclFrame
sirntar Dec 11, 2023
9bd763b
[RISC-V] Implement memory page stack probing
sirntar Dec 11, 2023
ea9555d
[RISC-V] OSR cleanup
sirntar Dec 12, 2023
7e999bf
[RISC-V] Improve genAllocLclFrame implementation
sirntar Dec 13, 2023
07feeaf
[RISC-V] Improve support for non standard memory pages and code clarity
sirntar Dec 15, 2023
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[RISC-V] Improve genAllocLclFrame implementation
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@sirntar
sirntar committed Dec 13, 2023
commit 7e999bf5d8529d3c7be2354bc81e8ac02a67517d
4 changes: 2 additions & 2 deletions src/coreclr/jit/codegen.h
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Original file line number Diff line number Diff line change
Expand Up @@ -343,8 +343,8 @@ class CodeGen final : public CodeGenInterface
#endif // TARGET_AMD64

#if defined(TARGET_RISCV64)
void genSmallStackProbe(ssize_t probeOffset, regNumber rOffset, regNumber rTemp);
void genStackProbe(ssize_t frameSize, regNumber rOffset, regNumber rLimit, regNumber rPageSize, regNumber rTemp);
void genSmallStackProbe(ssize_t probeOffset, regNumber rOffset);
void genStackProbe(ssize_t frameSize, regNumber rOffset, regNumber rLimit, regNumber rPageSize);
#endif

void genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pInitRegZeroed, regMaskTP maskArgRegsLiveIn);
Expand Down
120 changes: 57 additions & 63 deletions src/coreclr/jit/codegenriscv64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -841,8 +841,8 @@ void CodeGen::genFuncletProlog(BasicBlock* block)

compiler->unwindBegProlog();

bool isFilter = (block->bbCatchTyp == BBCT_FILTER);
int frameSize = genFuncletInfo.fiSpDelta;
const bool isFilter = (block->bbCatchTyp == BBCT_FILTER);
const int frameSize = genFuncletInfo.fiSpDelta;

assert(frameSize < 0);

Expand Down Expand Up @@ -982,7 +982,7 @@ void CodeGen::genFuncletEpilog()

compiler->unwindBegEpilog();

int frameSize = genFuncletInfo.fiSpDelta;
const int frameSize = genFuncletInfo.fiSpDelta;

assert(frameSize < 0);

Expand Down Expand Up @@ -2207,8 +2207,6 @@ void CodeGen::genLclHeap(GenTree* tree)
// addi regCnt, REG_R0, 0
//
// Skip:
// sub regCnt, SP, regCnt
//
// lui regTmp, eeGetPageSize()>>12
// Loop:
// lw r0, 0(SP) // tickle the page - read from the page
Expand All @@ -2229,7 +2227,7 @@ void CodeGen::genLclHeap(GenTree* tree)
assert(regCnt != tempReg);
emit->emitIns_R_R_R(INS_sltu, EA_PTRSIZE, tempReg, REG_SPBASE, regCnt);

//// subu regCnt, SP, regCnt // regCnt now holds ultimate SP
// sub regCnt, SP, regCnt // regCnt now holds ultimate SP
emit->emitIns_R_R_R(INS_sub, EA_PTRSIZE, regCnt, REG_SPBASE, regCnt);

// Overflow, set regCnt to lowest possible value
Expand Down Expand Up @@ -7484,29 +7482,23 @@ void CodeGen::genEstablishFramePointer(int delta, bool reportUnwindData)
// Arguments:
// probeOffset - current probe offset
// rOffset - usually initial register number
// rTemp - temporary register, usually REG_T9
//
void CodeGen::genSmallStackProbe(ssize_t probeOffset, regNumber rOffset, regNumber rTemp)
void CodeGen::genSmallStackProbe(ssize_t probeOffset, regNumber rOffset)
{
if (!(probeOffset & 0xfff))
if (emitter::isValidSimm12(-probeOffset))
{
// Tipical page size on risc-v is 4KB = 2^12 bytes
// Using that fact we will implement a little optimization trick
assert(probeOffset == ((probeOffset >> 12) << 12));

GetEmitter()->emitIns_R_I(INS_lui, EA_PTRSIZE, rOffset, -probeOffset >> 12);
GetEmitter()->emitIns_R_R_I(INS_addi, EA_PTRSIZE, rOffset, REG_SPBASE, -probeOffset);
regSet.verifyRegUsed(rOffset);
GetEmitter()->emitIns_R_R_R(INS_add, EA_PTRSIZE, rTemp, REG_SPBASE, rOffset);
// tickle the page - Read from the updated SP - this triggers a page fault when on the guard page
GetEmitter()->emitIns_R_R_I(INS_lw, EA_4BYTE, REG_R0, rTemp, 0);
GetEmitter()->emitIns_R_R_I(INS_lw, EA_4BYTE, REG_R0, rOffset, 0);
}
else
{
GetEmitter()->emitLoadImmediate(EA_PTRSIZE, rOffset, -(ssize_t)probeOffset);
GetEmitter()->emitLoadImmediate(EA_PTRSIZE, rOffset, -probeOffset);
regSet.verifyRegUsed(rOffset);
GetEmitter()->emitIns_R_R_R(INS_add, EA_PTRSIZE, rTemp, REG_SPBASE, rOffset);
GetEmitter()->emitIns_R_R_R(INS_add, EA_PTRSIZE, rOffset, REG_SPBASE, rOffset);
// tickle the page - Read from the updated SP - this triggers a page fault when on the guard page
GetEmitter()->emitIns_R_R_I(INS_lw, EA_4BYTE, REG_R0, rTemp, 0);
GetEmitter()->emitIns_R_R_I(INS_lw, EA_4BYTE, REG_R0, rOffset, 0);
}
}

Expand All @@ -7517,52 +7509,54 @@ void CodeGen::genSmallStackProbe(ssize_t probeOffset, regNumber rOffset, regNumb
// This function is using loop to probe each memory page.
//
// Arguments:
// frameSize - current probe offset
// frameSize - total frame size
// rOffset - usually initial register number
// rLimit - an extra register for comparison
// rPageSize - register for storing page size
// rTemp - temporary register, usually REG_T9
// rPageSize - register for storing page size if !emitter::isValidSimm12(-pageSize)
//
void CodeGen::genStackProbe(ssize_t frameSize, regNumber rOffset, regNumber rLimit, regNumber rPageSize, regNumber rTemp)
void CodeGen::genStackProbe(ssize_t frameSize, regNumber rOffset, regNumber rLimit, regNumber rPageSize)
{
const target_size_t pageSize = compiler->eeGetPageSize();
const ssize_t pageSize = (ssize_t)compiler->eeGetPageSize();
const bool isPageSize12bits = emitter::isValidSimm12(-pageSize);

// make sure frameSize safely fits within 4 bytes
noway_assert((ssize_t)(int)frameSize == (ssize_t)frameSize);

if (!(pageSize & 0xfff))
{
const ssize_t shiftedPageSize = (ssize_t)pageSize >> 12;

// Tipical page size on risc-v is 4KB = 2^12 bytes
// Using that fact we will implement a little optimization trick
assert(pageSize == (shiftedPageSize << 12));
GetEmitter()->emitLoadImmediate(EA_PTRSIZE, rLimit, -frameSize);
regSet.verifyRegUsed(rLimit);

GetEmitter()->emitIns_R_I(INS_lui, EA_PTRSIZE, rOffset, -shiftedPageSize);
if (isPageSize12bits)
{
GetEmitter()->emitIns_R_R_I(INS_addi, EA_PTRSIZE, rOffset, REG_SPBASE, -pageSize);
regSet.verifyRegUsed(rOffset);
GetEmitter()->emitIns_R_I(INS_lui, EA_PTRSIZE, rPageSize, shiftedPageSize);
regSet.verifyRegUsed(rPageSize);
}
else
{
GetEmitter()->emitLoadImmediate(EA_PTRSIZE, rOffset, -pageSize);
regSet.verifyRegUsed(rOffset);
GetEmitter()->emitIns_R_R_R(INS_add, EA_PTRSIZE, rOffset, REG_SPBASE, rOffset);

GetEmitter()->emitLoadImmediate(EA_PTRSIZE, rPageSize, pageSize);
regSet.verifyRegUsed(rPageSize);
}

GetEmitter()->emitLoadImmediate(EA_PTRSIZE, rLimit, -(ssize_t)frameSize);
regSet.verifyRegUsed(rLimit);

// Loop:
GetEmitter()->emitIns_R_R_R(INS_add, EA_PTRSIZE, rTemp, REG_SPBASE, rOffset);

// tickle the page - Read from the updated SP - this triggers a page fault when on the guard page
GetEmitter()->emitIns_R_R_I(INS_lw, EA_4BYTE, REG_R0, rTemp, 0);
GetEmitter()->emitIns_R_R_R(INS_sub, EA_PTRSIZE, rOffset, rOffset, rPageSize);
GetEmitter()->emitIns_R_R_I(INS_lw, EA_4BYTE, REG_R0, rOffset, 0);

if (isPageSize12bits)
{
GetEmitter()->emitIns_R_R_I(INS_addi, EA_PTRSIZE, rOffset, rOffset, -pageSize);
}
else
{
GetEmitter()->emitIns_R_R_R(INS_sub, EA_PTRSIZE, rOffset, rOffset, rPageSize);
}

// each instr is 4 bytes
// if (rOffset >= rLimit) goto Loop;
GetEmitter()->emitIns_R_R_I(INS_bge, EA_PTRSIZE, rOffset, rLimit, -3 << 2);
GetEmitter()->emitIns_R_R_I(INS_bge, EA_PTRSIZE, rOffset, rLimit, -2 << 2);
}

//------------------------------------------------------------------------
Expand All @@ -7581,16 +7575,6 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni

assert(!compiler->info.compPublishStubParam || (REG_SECRET_STUB_PARAM != initReg));

regMaskTP availMask = RBM_ALLINT & (regSet.rsGetModifiedRegsMask() | ~RBM_INT_CALLEE_SAVED);
availMask &= ~maskArgRegsLiveIn; // Remove all of the incoming argument registers
// as they are currently live
availMask &= ~genRegMask(initReg); // Remove the pre-calculated initReg

noway_assert(availMask != RBM_NONE);

regMaskTP tempMask = genFindLowestBit(availMask);
regNumber tempReg = genRegNumFromMask(tempMask);

target_size_t lastTouchDelta = 0;

// Emit the following sequence to 'tickle' the pages.
Expand All @@ -7611,7 +7595,7 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni

for (target_size_t probeOffset = pageSize; probeOffset <= frameSize; probeOffset += pageSize)
{
genSmallStackProbe((ssize_t)probeOffset, initReg, tempReg);
genSmallStackProbe((ssize_t)probeOffset, initReg);
lastTouchDelta -= pageSize;
}

Expand All @@ -7623,22 +7607,32 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni
}
else
{
// using two scratch regs, probe each page, that we need to allocate large stack frame
// probe each page, that we need to allocate large stack frame
assert(frameSize >= 3 * pageSize);

availMask &= ~tempMask; // Remove tempReg register
noway_assert(availMask != RBM_NONE); // We need one more register for limit condition
tempMask = genFindLowestBit(availMask);
regMaskTP availMask = RBM_ALLINT & (regSet.rsGetModifiedRegsMask() | ~RBM_INT_CALLEE_SAVED);
availMask &= ~maskArgRegsLiveIn; // Remove all of the incoming argument registers
// as they are currently live
availMask &= ~genRegMask(initReg); // Remove the pre-calculated initReg

regNumber rLimit = genRegNumFromMask(tempMask);
noway_assert(availMask != RBM_NONE);

regMaskTP regMask = genFindLowestBit(availMask);

regNumber rLimit = genRegNumFromMask(regMask);
regNumber rPageSize = REG_NA;

availMask &= ~tempMask; // Remove rLimit register
noway_assert(availMask != RBM_NONE); // We need one more register for storing page size
tempMask = genFindLowestBit(availMask);
if (!emitter::isValidSimm12(-pageSize))
{
availMask &= ~regMask; // Remove rLimit register

noway_assert(availMask != RBM_NONE);

regNumber rPageSize = genRegNumFromMask(tempMask);
regMask = genFindLowestBit(availMask);
rPageSize = genRegNumFromMask(regMask);
}

genStackProbe(frameSize, initReg, rLimit, rPageSize, tempReg);
genStackProbe((ssize_t)frameSize, initReg, rLimit, rPageSize);

assert(pInitRegZeroed != nullptr);
*pInitRegZeroed = false; // The initReg does not contain zero
Expand All @@ -7654,7 +7648,7 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni
// on linux there is only one guard page, which we shouldn't skip
assert(deltaSize < pageSize << 1);

genSmallStackProbe(-(ssize_t)frameSize, initReg, tempReg);
genSmallStackProbe((ssize_t)frameSize, initReg);

assert(pInitRegZeroed != nullptr);
*pInitRegZeroed = false; // The initReg does not contain zero
Expand Down