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Merge pull request #20322 from dchopra001/ffi_incStackCounterForStructs
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Increment stackSlotCount for structs correctly in FFI upcall on z/OS
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@keithc-ca
keithc-ca authored Nov 5, 2024
2 parents 33c0833 + 99f0667 commit 05acdf0
Showing 1 changed file with 27 additions and 37 deletions.
64 changes: 27 additions & 37 deletions runtime/vm/mz64/UpcallThunkGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -269,11 +269,11 @@ createUpcallThunk(J9UpcallMetaData *metaData)
}
metaData->thunkAddress = (void *)thunkMem;

I_32 gprIndex = 1;
const I_32 maxGPRIndex = 3;
I_32 fprIndex = 0;
const I_32 maxFPRIndex = 6;
I_32 currStackSlotIndex = 0;
U_32 gprIndex = 1;
const U_32 maxGPRIndex = 3;
U_32 fprIndex = 0;
const U_32 maxFPRIndex = 6;
U_32 currStackSlotIndex = 0;

// Now we loop through the arguments and generate the actual instructions to store any register arguments in the caller frame.
const I_32 numRegsToPreserve = 10;
Expand All @@ -287,7 +287,8 @@ createUpcallThunk(J9UpcallMetaData *metaData)
}
for (I_32 i = 0; i < lastSigIdx; i++) {
U_32 argSizeInBytes = sigArray[i].sizeInByte;
switch(sigArray[i].type) {
const U_32 totalStackSlotsReq = (argSizeInBytes + 7) / 8;
switch (sigArray[i].type) {
case J9_FFI_UPCALL_SIG_TYPE_CHAR: /* Fall through */
case J9_FFI_UPCALL_SIG_TYPE_SHORT: /* Fall through */
case J9_FFI_UPCALL_SIG_TYPE_INT32: /* Fall through */
Expand Down Expand Up @@ -328,33 +329,28 @@ createUpcallThunk(J9UpcallMetaData *metaData)
if (fprIndex <= maxFPRIndex - 2) {
thunkMem += STEY(thunkMem, fprIndex, 0, R4, argAreaOffsetFromSP + (currStackSlotIndex * 8));
thunkMem += STEY(thunkMem, fprIndex + 2, 0, R4, argAreaOffsetFromSP + (currStackSlotIndex * 8) + 4);
currStackSlotIndex += 1;
fprIndex += 4;
if (i < 3) {
gprIndex += 2;
}
}
else if (fprIndex <= maxFPRIndex) {
thunkMem += STEY(thunkMem, fprIndex, 0, R4, argAreaOffsetFromSP + (currStackSlotIndex * 8));
currStackSlotIndex += 1;
fprIndex += 2;
}
}
else { // All other pure float structs are passed in GPR (if there's space)
if (gprIndex <= maxGPRIndex) {
int totalStackSlotsReq = ((argSizeInBytes - 1) / 8) + 1;
int numGPRsAvailable = maxGPRIndex - gprIndex + 1;
int tempArgIndex = currStackSlotIndex;
for (int i = 1; i <= std::min(numGPRsAvailable, totalStackSlotsReq); i++) {
U_32 numGPRsAvailable = maxGPRIndex - gprIndex + 1;
U_32 tempArgIndex = currStackSlotIndex;
for (U_32 i = 1; i <= std::min(numGPRsAvailable, totalStackSlotsReq); i++) {
thunkMem += STG(thunkMem, gprIndex, 0, R4, argAreaOffsetFromSP + (tempArgIndex * 8));
tempArgIndex += 1;
gprIndex++;
}

// increase currStackSlotIndex by the number of slots this struct takes in memory
currStackSlotIndex += totalStackSlotsReq;
}
}
currStackSlotIndex += totalStackSlotsReq;
break;
case J9_FFI_UPCALL_SIG_TYPE_STRUCT_AGGREGATE_ALL_DP:
if (argSizeInBytes == 2 * sizeof(double)) {
Expand All @@ -364,34 +360,30 @@ createUpcallThunk(J9UpcallMetaData *metaData)
// argument area.
if (fprIndex <= maxFPRIndex - 2) {
thunkMem += STDY(thunkMem, fprIndex, 0, R4, argAreaOffsetFromSP + (currStackSlotIndex * 8));
currStackSlotIndex += 1;
thunkMem += STDY(thunkMem, fprIndex + 2, 0, R4, argAreaOffsetFromSP + (currStackSlotIndex * 8));
currStackSlotIndex += 1;
thunkMem += STDY(thunkMem, fprIndex + 2, 0, R4, argAreaOffsetFromSP + ((currStackSlotIndex + 1) * 8));
fprIndex += 4;
if (i < 3) {
gprIndex += 2;
}
}
else if (fprIndex <= maxFPRIndex) {
thunkMem += STDY(thunkMem, fprIndex, 0, R4, argAreaOffsetFromSP + (currStackSlotIndex * 8));
currStackSlotIndex += 1;
fprIndex += 2;
}
}
else { // This is for all other pure double structs (they will be passed in GPRs if there's space)
if (gprIndex <= maxGPRIndex) {
int totalStackSlotsReq = argSizeInBytes / 8; // the size in bytes for a struct with only doubles will always be a multiple of 8.
int numGPRsAvailable = maxGPRIndex - gprIndex + 1;
int tempArgIndex = currStackSlotIndex;
for (int i = 1; i <= std::min(numGPRsAvailable, totalStackSlotsReq); i++) {
thunkMem += STG(thunkMem, gprIndex, 0, R4, argAreaOffsetFromSP + (tempArgIndex * 8));
tempArgIndex += 1;
gprIndex++;
else { // This is for all other pure double structs (they will be passed in GPRs if there's space)
if (gprIndex <= maxGPRIndex) {
U_32 numGPRsAvailable = maxGPRIndex - gprIndex + 1;
U_32 tempArgIndex = currStackSlotIndex;
for (U_32 i = 1; i <= std::min(numGPRsAvailable, totalStackSlotsReq); i++) {
thunkMem += STG(thunkMem, gprIndex, 0, R4, argAreaOffsetFromSP + (tempArgIndex * 8));
tempArgIndex += 1;
gprIndex++;
}
// increase currStackSlotIndex by the number of slots this struct takes in memory
}
// increase currStackSlotIndex by the number of slots this struct takes in memory
currStackSlotIndex += totalStackSlotsReq;
}
}
currStackSlotIndex += totalStackSlotsReq;
break;
case J9_FFI_UPCALL_SIG_TYPE_STRUCT_AGGREGATE_SP_DP:
case J9_FFI_UPCALL_SIG_TYPE_STRUCT_AGGREGATE_SP_SP_DP:
Expand All @@ -404,17 +396,15 @@ createUpcallThunk(J9UpcallMetaData *metaData)
case J9_FFI_UPCALL_SIG_TYPE_STRUCT_AGGREGATE_OTHER:
case J9_FFI_UPCALL_SIG_TYPE_STRUCT_AGGREGATE_MISC:
if (gprIndex <= maxGPRIndex) {
int totalStackSlotsReq = ((argSizeInBytes - 1) / 8) + 1;
int numGPRsAvailable = maxGPRIndex - gprIndex + 1;
int tempArgIndex = currStackSlotIndex;
for (int i = 1; i <= std::min(numGPRsAvailable, totalStackSlotsReq); i++) {
U_32 numGPRsAvailable = maxGPRIndex - gprIndex + 1;
U_32 tempArgIndex = currStackSlotIndex;
for (U_32 i = 1; i <= std::min(numGPRsAvailable, totalStackSlotsReq); i++) {
thunkMem += STG(thunkMem, gprIndex, 0, R4, argAreaOffsetFromSP + (tempArgIndex * 8));
tempArgIndex += 1;
gprIndex++;
}
// increase currStackSlotIndex by the number of slots this struct takes in memory
currStackSlotIndex += totalStackSlotsReq;
}
currStackSlotIndex += totalStackSlotsReq;
break;
default:
Assert_VM_unreachable();
Expand Down

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