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Add support for structs in FFI Upcall on z/OS
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@dchopra001
dchopra001 committed Jul 30, 2024
1 parent bd018c0 commit 5c43fb0
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Showing 3 changed files with 621 additions and 317 deletions.
222 changes: 174 additions & 48 deletions runtime/oti/FFIUpcallThunkGenHelpers.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
#if !defined(FFIUPCALLTHUNKGENHELPERS_HPP_)
#define FFIUPCALLTHUNKGENHELPERS_HPP_

#define R0 0
#define R1 1
#define R2 2
#define R3 3
Expand All @@ -35,6 +36,42 @@
#define MAX_MVC_COPY_LENGTH 256
#define MAX_MVC_DISPLACEMENT 4096

/**
* Generates an instruction to load a double precision floating point value into GPR.
* Format: "LD R1,D2(X2,B2)"
* R1 - destinationRegister
* D2 - displacementInteger
* X2 - offsetRegister
* B2 - baseRegister
*
* Returns: instruction size in bytes
*/
I_32
LD(I_8 *instructionPtr, I_32 destinationRegister, I_32 offsetRegister, I_32 baseRegister, I_32 displacementInteger)
{
I_32 opcode = 0x68000000;
*((I_32 *)instructionPtr) = opcode | ((destinationRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | ((displacementInteger & 0xFFF));
return 4;
}

/**
* Generates an instruction to load a single precision floating point value into GPR.
* Format: "LE R1,D2(X2,B2)"
* R1 - destinationRegister
* D2 - displacementInteger
* X2 - offsetRegister
* B2 - baseRegister
*
* Returns: instruction size in bytes
*/
I_32
LE(I_8 *instructionPtr, I_32 destinationRegister, I_32 offsetRegister, I_32 baseRegister, I_32 displacementInteger)
{
I_32 opcode = 0x78000000;
*((I_32 *)instructionPtr) = opcode | ((destinationRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | ((displacementInteger & 0xFFF));
return 4;
}

/**
* Generates an instruction to store a double precision floating point value to memory.
* Format: "STDY R1,D2(X2,B2)"
Expand All @@ -48,11 +85,11 @@
I_32
STDY(I_8 *instructionPtr, I_32 valueRegister, I_32 offsetRegister, I_32 baseRegister, I_32 displacementInteger)
{
I_32 opcode = 0xED000000;
*((I_32 *)instructionPtr) = opcode | ((valueRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x67;
return 6;
I_32 opcode = 0xED000000;
*((I_32 *)instructionPtr) = opcode | ((valueRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x67;
return 6;
}

/**
Expand All @@ -66,8 +103,8 @@ STDY(I_8 *instructionPtr, I_32 valueRegister, I_32 offsetRegister, I_32 baseRegi
I_32
BCR(I_8 *instructionPtr, I_16 conditionMask, I_16 destinationRegister)
{
*((I_16 *)instructionPtr) = 0x0700 | ((conditionMask & 0x000F) << 4) | (destinationRegister & 0x000F);
return 2;
*((I_16 *)instructionPtr) = 0x0700 | ((conditionMask & 0x000F) << 4) | (destinationRegister & 0x000F);
return 2;
}

/**
Expand All @@ -83,10 +120,10 @@ BCR(I_8 *instructionPtr, I_16 conditionMask, I_16 destinationRegister)
I_32
STEY(I_8 *instructionPtr, I_32 valueRegister, I_32 offsetRegister, I_32 baseRegister, I_32 displacementInteger)
{
*((I_32 *)instructionPtr) = 0xED000000 | ((valueRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x66;
return 6;
*((I_32 *)instructionPtr) = 0xED000000 | ((valueRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x66;
return 6;
}

/**
Expand All @@ -102,10 +139,10 @@ STEY(I_8 *instructionPtr, I_32 valueRegister, I_32 offsetRegister, I_32 baseRegi
I_32
LAY(I_8 *instructionPtr, I_32 destinationRegister, I_32 offsetRegister, I_32 baseRegister, I_32 displacementInteger)
{
*((I_32 *)instructionPtr) = 0xE3000000 | ((destinationRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x71;
return 6;
*((I_32 *)instructionPtr) = 0xE3000000 | ((destinationRegister & 0xF) << 20) | ((offsetRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x71;
return 6;
}

/**
Expand All @@ -119,9 +156,9 @@ LAY(I_8 *instructionPtr, I_32 destinationRegister, I_32 offsetRegister, I_32 bas
I_32
BASR(I_8 *instructionPtr, I_32 returnAddressRegister, I_32 destinationRegister)
{
I_16 opcode = 0x0D00;
*((I_16 *)instructionPtr) = (opcode | (((I_16)returnAddressRegister) << 4) | (((I_16)destinationRegister)));
return 2;
I_16 opcode = 0x0D00;
*((I_16 *)instructionPtr) = (opcode | (((I_16)returnAddressRegister) << 4) | (((I_16)destinationRegister)));
return 2;
}

/**
Expand All @@ -135,11 +172,11 @@ BASR(I_8 *instructionPtr, I_32 returnAddressRegister, I_32 destinationRegister)
I_32
IIHF(I_8 *instructionPtr, I_32 destinationRegister, I_32 integerConstant)
{
I_32 opcode = 0xC008;
*((I_16 *)instructionPtr) = (opcode | (I_16)(destinationRegister << 4));
instructionPtr += 2;
*((I_32 *)instructionPtr) = integerConstant;
return 6;
I_32 opcode = 0xC008;
*((I_16 *)instructionPtr) = (opcode | (I_16)(destinationRegister << 4));
instructionPtr += 2;
*((I_32 *)instructionPtr) = integerConstant;
return 6;
}

/**
Expand All @@ -153,11 +190,11 @@ IIHF(I_8 *instructionPtr, I_32 destinationRegister, I_32 integerConstant)
I_32
IILF(I_8 *instructionPtr, I_32 destinationRegister, I_32 integerConstant)
{
I_32 opcode = 0xC009;
*((I_16 *)instructionPtr) = (opcode | (I_16)(destinationRegister << 4));
instructionPtr += 2;
*((I_32 *)instructionPtr) = integerConstant;
return 6;
I_32 opcode = 0xC009;
*((I_16 *)instructionPtr) = (opcode | (I_16)(destinationRegister << 4));
instructionPtr += 2;
*((I_32 *)instructionPtr) = integerConstant;
return 6;
}


Expand All @@ -174,11 +211,11 @@ IILF(I_8 *instructionPtr, I_32 destinationRegister, I_32 integerConstant)
I_32
STG(I_8 *instructionPtr, I_32 sourceRegister, I_32 offsetRegister, I_32 baseRegister, I_32 displacementInteger)
{
I_32 opcode = 0xE3000000;
*((I_32 *)instructionPtr) = (opcode | (sourceRegister << 20) | (offsetRegister << 16) | (baseRegister << 12) | (displacementInteger & 0x00000FFF));
instructionPtr[4] = (I_8)((displacementInteger & 0x000FF000) >> 12);
instructionPtr[5] = 0x24;
return 6;
I_32 opcode = 0xE3000000;
*((I_32 *)instructionPtr) = (opcode | (sourceRegister << 20) | (offsetRegister << 16) | (baseRegister << 12) | (displacementInteger & 0x00000FFF));
instructionPtr[4] = (I_8)((displacementInteger & 0x000FF000) >> 12);
instructionPtr[5] = 0x24;
return 6;
}

/**
Expand Down Expand Up @@ -216,11 +253,11 @@ BC(I_8 *instructionPtr, I_32 mask1, I_32 offsetRegister, I_32 destinationRegiste
I_32
STMG(I_8 *instructionPtr, I_32 startRegister, I_32 endRegister, I_32 baseRegister, I_32 displacementInteger) // zos
{
I_32 opcode = 0xEB000000;
*((I_32 *)instructionPtr) = opcode | ((startRegister & 0xF) << 20) | ((endRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x24;
return 6;
I_32 opcode = 0xEB000000;
*((I_32 *)instructionPtr) = opcode | ((startRegister & 0xF) << 20) | ((endRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x24;
return 6;
}

/**
Expand All @@ -237,11 +274,11 @@ STMG(I_8 *instructionPtr, I_32 startRegister, I_32 endRegister, I_32 baseRegiste
I_32
LMG(I_8 *instructionPtr, I_32 startRegister, I_32 endRegister, I_32 baseRegister, I_32 displacementInteger) // zos
{
I_32 opcode = 0xEB000000;
*((I_32 *)instructionPtr) = opcode | ((startRegister & 0xF) << 20) | ((endRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x04;
return 6;
I_32 opcode = 0xEB000000;
*((I_32 *)instructionPtr) = opcode | ((startRegister & 0xF) << 20) | ((endRegister & 0xF) << 16) | ((baseRegister & 0xF) << 12) | (displacementInteger & 0xFFF);
instructionPtr[4] = ((displacementInteger & 0xFF000) >> 12);
instructionPtr[5] = 0x04;
return 6;
}

/**
Expand All @@ -257,11 +294,11 @@ LMG(I_8 *instructionPtr, I_32 startRegister, I_32 endRegister, I_32 baseRegister
I_32
LG(I_8 *instructionPtr, I_32 destinationRegister, I_32 offsetRegister, I_32 baseRegister, I_32 displacementInteger)
{
I_32 opcode = 0xE3000000;
*((I_32 *)instructionPtr) = (opcode | (destinationRegister << 20) | (offsetRegister << 16) | (baseRegister << 12) | (displacementInteger & 0x00000FFF));
instructionPtr[4] = (I_8)((displacementInteger & 0x000FF000) >> 12);
instructionPtr[5] = 0x04;
return 6;
I_32 opcode = 0xE3000000;
*((I_32 *)instructionPtr) = (opcode | (destinationRegister << 20) | (offsetRegister << 16) | (baseRegister << 12) | (displacementInteger & 0x00000FFF));
instructionPtr[4] = (I_8)((displacementInteger & 0x000FF000) >> 12);
instructionPtr[5] = 0x04;
return 6;
}

/*
Expand Down Expand Up @@ -323,4 +360,93 @@ AFI(I_8 *instructionPtr, I_32 sourceRegister, I_32 immediateInteger)

}

/*
* Generates a sequence of instructions to copy data from a Java MemorySegment Object to a C struct.
* The struct is smaller than or equal to 4096 bytes.
*/
static I_32
generateSmallStructCopyInstructions(I_8 *instructionPtr, I_32 structSize, I_32 offsetToParameterArea, I_32 sourceRegister, I_32 destinationRegister)
{
I_32 totalInstructionSize = 0;

const I_32 numLargeCopies = structSize / MAX_MVC_COPY_LENGTH;
const I_32 residue = structSize % MAX_MVC_COPY_LENGTH;

// Generate upto 16 MVC instructions to copy up 4096 bytes. Each MVC instruction in this sequence will copy 256 bytes.
for(int i = 0; i < numLargeCopies; i++) {
// MVC D1(L,B1),D2(B2)
// The 'L' field is 0-based
totalInstructionSize += MVC(instructionPtr + totalInstructionSize, i * MAX_MVC_COPY_LENGTH, MAX_MVC_COPY_LENGTH - 1, destinationRegister, i * MAX_MVC_COPY_LENGTH, sourceRegister);
}
// Generate an instruction to copy the last set of bytes (less than 256).
if (residue != 0) {
// MVC D1(L,B1),D2(B2)
totalInstructionSize += MVC(instructionPtr + totalInstructionSize, numLargeCopies * MAX_MVC_COPY_LENGTH, residue - 1, destinationRegister, numLargeCopies * MAX_MVC_COPY_LENGTH, sourceRegister);
}
return totalInstructionSize;
}

/*
* Generates a sequence of instructions to copy data from a Java MemorySegment Object to a C struct.
* The struct is larger than 4096 bytes.
*/
static I_32
generateLargeStructCopyInstructions(I_8 *instructionPtr, I_32 structSize, I_32 offsetToParameterArea, I_32 sourceRegister, I_32 destinationRegister)
{
I_32 totalInstructionSize = 0;

const I_32 numFullSlots = structSize / MAX_MVC_COPY_LENGTH;
const I_32 residue = structSize % MAX_MVC_COPY_LENGTH;
const I_32 maxLargeCopies = MAX_MVC_DISPLACEMENT / MAX_MVC_COPY_LENGTH;

const I_32 loopResidue = numFullSlots % maxLargeCopies;

// loopInstructionsLength = 16x MVC(6) + 2x LAY (6) + 1x AFI (6)
const I_32 loopInstructionsLength = 114; // size in bytes
I_32 destinationDisplacementInt = -1;
I_32 sourceDisplacementInt = -1;
I_32 currMVCLength = -1;

// Load loop counter into R3
totalInstructionSize += IILF(instructionPtr + totalInstructionSize, R0, numFullSlots - loopResidue);

// Generate a loop that will copy 4096 bytes at a time (i.e. 16 MVC instructions). The loop concludes when there
// are less than 4096 bytes left to copy.
for (int i = 0; i < maxLargeCopies; i++) {
// MVC D1(L,B1),D2(B2)
// The 'L' field is 0-based
destinationDisplacementInt = i * MAX_MVC_COPY_LENGTH;
currMVCLength = MAX_MVC_COPY_LENGTH - 1;
sourceDisplacementInt = i * MAX_MVC_COPY_LENGTH;
totalInstructionSize += MVC(instructionPtr + totalInstructionSize, destinationDisplacementInt, currMVCLength, destinationRegister, sourceDisplacementInt, sourceRegister);
}
totalInstructionSize += LAY(instructionPtr + totalInstructionSize, destinationRegister, 0, destinationRegister, MAX_MVC_DISPLACEMENT);
totalInstructionSize += LAY(instructionPtr + totalInstructionSize, sourceRegister, 0, sourceRegister, MAX_MVC_DISPLACEMENT);
totalInstructionSize += AFI(instructionPtr + totalInstructionSize, R0, -maxLargeCopies);

const I_32 conditionMask = 7;
totalInstructionSize += BRCL(instructionPtr + totalInstructionSize, conditionMask, -(loopInstructionsLength/2));

// If numberOfBytesLeftToCopy > 256 && numberOfBytesLeftToCopy < 4096, then we generate the appropriate number of MVC instructions to copy them sequentially below.
if (loopResidue > 0) {
for (I_32 i = 0; i < loopResidue; i++) {
// MVC D1(L,B1),D2(B2)
destinationDisplacementInt = i * MAX_MVC_COPY_LENGTH;
currMVCLength = MAX_MVC_COPY_LENGTH - 1;
sourceDisplacementInt = i * MAX_MVC_COPY_LENGTH;
totalInstructionSize += MVC(instructionPtr + totalInstructionSize, destinationDisplacementInt, currMVCLength, destinationRegister, sourceDisplacementInt, sourceRegister);
}
}

// If numberOfBytesLeftToCopy < 256 then we generate an instruction here to copy those bytes over.
if (residue != 0) {
// MVC D1(L,B1),D2(B2)
destinationDisplacementInt = loopResidue > 0 ? loopResidue * MAX_MVC_COPY_LENGTH : (numFullSlots - maxLargeCopies) * MAX_MVC_COPY_LENGTH;
currMVCLength = residue - 1;
sourceDisplacementInt = loopResidue > 0 ? loopResidue * MAX_MVC_COPY_LENGTH : (numFullSlots - maxLargeCopies) * MAX_MVC_COPY_LENGTH;
totalInstructionSize += MVC(instructionPtr + totalInstructionSize, destinationDisplacementInt, currMVCLength, destinationRegister, sourceDisplacementInt, sourceRegister);
}
return totalInstructionSize;
}

#endif /* FFIUPCALLTHUNKGENHELPERS_HPP_ */
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