[OpenMP] Don't emit redundant zero-sized mapping nodes for overlapped structs (#148947)
The handling of overlapped structure mapping in CGOpenMPRuntime.cpp can
lead to redundant zero-sized mapping nodes at runtime. This patch fixes
it using a combination of approaches: trivially adjacent struct members
won't have a mapping node created between them, and for more complicated
cases (inheritance) the physical layout of the struct/class is used to
make sure that elements aren't missed.
I've introduced a new class to track the state whilst iterating over the
struct. This reduces a bit of redundancy in the code (accumulating
CombinedInfo both during and after the loop), which I think is a bit
neater.
Before:
omptarget --> Entry 0: Base=0x00007fff8d483830, Begin=0x00007fff8d483830, Size=48, Type=0x20, Name=unknown
omptarget --> Entry 1: Base=0x00007fff8d483830, Begin=0x00007fff8d483830, Size=0, Type=0x1000000000003, Name=unknown
omptarget --> Entry 2: Base=0x00007fff8d483830, Begin=0x00007fff8d483834, Size=0, Type=0x1000000000003, Name=unknown
omptarget --> Entry 3: Base=0x00007fff8d483830, Begin=0x00007fff8d483838, Size=0, Type=0x1000000000003, Name=unknown
omptarget --> Entry 4: Base=0x00007fff8d483830, Begin=0x00007fff8d48383c, Size=20, Type=0x1000000000003, Name=unknown
omptarget --> Entry 5: Base=0x00007fff8d483830, Begin=0x00007fff8d483854, Size=0, Type=0x1000000000003, Name=unknown
omptarget --> Entry 6: Base=0x00007fff8d483830, Begin=0x00007fff8d483858, Size=0, Type=0x1000000000003, Name=unknown
omptarget --> Entry 7: Base=0x00007fff8d483830, Begin=0x00007fff8d48385c, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 8: Base=0x00007fff8d483830, Begin=0x00007fff8d483830, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 9: Base=0x00007fff8d483830, Begin=0x00007fff8d483834, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 10: Base=0x00007fff8d483830, Begin=0x00007fff8d483838, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 11: Base=0x00007fff8d483840, Begin=0x00005e7665275130, Size=32, Type=0x1000000000013, Name=unknown
omptarget --> Entry 12: Base=0x00007fff8d483830, Begin=0x00007fff8d483850, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 13: Base=0x00007fff8d483830, Begin=0x00007fff8d483854, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 14: Base=0x00007fff8d483830, Begin=0x00007fff8d483858, Size=4, Type=0x1000000000003, Name=unknown
After:
omptarget --> Entry 0: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f562e0, Size=48, Type=0x20, Name=unknown
omptarget --> Entry 1: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f562ec, Size=20, Type=0x1000000000003, Name=unknown
omptarget --> Entry 2: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f5630c, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 3: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f562e0, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 4: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f562e4, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 5: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f562e8, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 6: Base=0x00007fffd0f562f0, Begin=0x000058b6013fb130, Size=32, Type=0x1000000000013, Name=unknown
omptarget --> Entry 7: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f56300, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 8: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f56304, Size=4, Type=0x1000000000003, Name=unknown
omptarget --> Entry 9: Base=0x00007fffd0f562e0, Begin=0x00007fffd0f56308, Size=4, Type=0x1000000000003, Name=unknown
For code:
#include <cstdlib>
#include <cstdio>
struct S {
int x;
int y;
int z;
int *p1;
int *p2;
};
struct T : public S {
int a;
int b;
int c;
};
int main() {
T v;
v.p1 = (int*) calloc(8, sizeof(int));
v.p2 = (int*) calloc(8, sizeof(int));
#pragma omp target map(tofrom: v, v.x, v.y, v.z, v.p1[:8], v.a, v.b, v.c)
{
v.x++;
v.y += 2;
v.z += 3;
v.p1[0] += 4;
v.a += 7;
v.b += 5;
v.c += 6;
}
return 0;
}
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