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Ben Gamari pushed to branch wip/T26502 at Glasgow Haskell Compiler / GHC

Commits:

064107a5

by Ben Gamari at 2025-10-14T12:04:48-04:00

rts: Eliminate uses of implicit constant arrays

Folding of `const`-sized variable-length arrays to a constant-length
array is a gnu extension which clang complains about.

Closes #26502.

2 changed files:

rts/Printer.c
rts/posix/OSMem.c

Changes:

rts/Printer.c

@@ -1033,8 +1033,8 @@ findPtr(P_ p, int follow)
+ {
    uint32_t g, n;
    bdescr *bd;
 -  const int arr_size = 1024;
 -  StgPtr arr[arr_size];
 +#define ARR_SIZE 1024
 +  StgPtr arr[ARR_SIZE];
    int i = 0;
    searched = 0;
@@ -1044,24 +1044,24 @@ findPtr(P_ p, int follow)
    // just before a block is used.
    for (n = 0; n < getNumCapabilities(); n++) {
        bd = nurseries[i].blocks;
 -      i = findPtrBlocks(p,bd,arr,arr_size,i);
 -      if (i >= arr_size) return;
 +      i = findPtrBlocks(p,bd,arr,ARR_SIZE,i);
 +      if (i >= ARR_SIZE) return;
+   }
  #endif
    for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
        bd = generations[g].blocks;
 -      i = findPtrBlocks(p,bd,arr,arr_size,i);
 +      i = findPtrBlocks(p,bd,arr,ARR_SIZE,i);
        bd = generations[g].large_objects;
 -      i = findPtrBlocks(p,bd,arr,arr_size,i);
 -      if (i >= arr_size) return;
 +      i = findPtrBlocks(p,bd,arr,ARR_SIZE,i);
 +      if (i >= ARR_SIZE) return;
        for (n = 0; n < getNumCapabilities(); n++) {
            i = findPtrBlocks(p, gc_threads[n]->gens[g].part_list,
 -                            arr, arr_size, i);
 +                            arr, ARR_SIZE, i);
            i = findPtrBlocks(p, gc_threads[n]->gens[g].todo_bd,
 -                            arr, arr_size, i);
 +                            arr, ARR_SIZE, i);
+       }
 -      if (i >= arr_size) return;
 +      if (i >= ARR_SIZE) return;
+   }
    if (follow && i == 1) {
        debugBelch("-->\n");

rts/posix/OSMem.c

@@ -585,7 +585,7 @@ void *osReserveHeapMemory(void *startAddressPtr, W_ *len)
+     }
  #endif
 -    const int MAX_ATTEMPTS = 256;
 +#define MAX_ATTEMPTS 256
      void *bad_allocs[MAX_ATTEMPTS];
      size_t bad_alloc_lens[MAX_ATTEMPTS];
      memset(bad_allocs, 0, sizeof(void*) * MAX_ATTEMPTS);