[Git][ghc/ghc][wip/T18857] fixup ShortText & SymbolExtras

[Moritz Angermann]

Moritz Angermann pushed to branch wip/T18857 at Glasgow Haskell Compiler / GHC


Commits:
047ee59e by Moritz Angermann at 2020-11-17T04:28:05+00:00
fixup ShortText & SymbolExtras

- - - - -


5 changed files:

- libraries/ghc-boot/GHC/Data/ShortText.hs
- rts/LinkerInternals.h
- rts/linker/Elf.c
- rts/linker/SymbolExtras.c
- rts/linker/elf_reloc_aarch64.c


Changes:

=====================================
libraries/ghc-boot/GHC/Data/ShortText.hs
=====================================
@@ -1,6 +1,22 @@
-{-# LANGUAGE BangPatterns, MagicHash, UnboxedTuples, GeneralizedNewtypeDeriving, DerivingStrategies #-}
+{-# LANGUAGE BangPatterns, MagicHash, UnboxedTuples, GeneralizedNewtypeDeriving, DerivingStrategies, CPP #-}
 {-# OPTIONS_GHC -O2 -funbox-strict-fields #-}
-
+-- gross hack: we manuvered ourselves into a position where we can't boot GHC with a LLVM based GHC anymore.
+-- LLVM based GHC's fail to compile memcmp ffi calls.  These end up as memcmp$def in the llvm ir, however we
+-- don't have any prototypes and subsequently the llvm toolchain chokes on them.  Since 7fdcce6d, we use
+-- ShortText for the package database.  This however introduces this very module; which through inlining ends
+-- up bringing memcmp_ByteArray from bytestring:Data.ByteString.Short.Internal into scope, which results in
+-- the memcmp call we choke on.
+--
+-- The solution thusly is to force late binding via the linker instead of inlining when comping with the
+-- bootstrap compiler.  This will produce a slower (slightly less optimised) stage1 compiler only.
+--
+-- See issue 18857. hsyl20 deserves credit for coming up with the idea for the soltuion.
+--
+-- This can be removed when we exit the boot compiler window. Thus once we drop GHC-9.2 as boot compiler,
+-- we can drop this code as well.
+#if GHC_STAGE < 1
+{-# OPTIONS_GHC -fignore-interface-pragmas #-}
+#endif
 -- |
 -- An Unicode string for internal GHC use. Meant to replace String
 -- in places where being a lazy linked is not very useful and a more


=====================================
rts/LinkerInternals.h
=====================================
@@ -141,7 +141,7 @@ typedef struct _Segment {
     int n_sections;
 } Segment;
 
-#if defined(powerpc_HOST_ARCH) || defined(x86_64_HOST_ARCH)
+#if defined(powerpc_HOST_ARCH) || defined(x86_64_HOST_ARCH) || defined(aarch64_HOST_ARCH)
 #define NEED_SYMBOL_EXTRAS 1
 #endif
 


=====================================
rts/linker/Elf.c
=====================================
@@ -940,7 +940,7 @@ ocGetNames_ELF ( ObjectCode* oc )
                    symbol->addr = (SymbolAddr*)(
                            (intptr_t) oc->sections[secno].start +
                            (intptr_t) symbol->elf_sym->st_value);
-
+                   ASSERT(symbol->addr != 0x0);
                    if (ELF_ST_BIND(symbol->elf_sym->st_info) == STB_LOCAL) {
                        isLocal = true;
                        isWeak = false;
@@ -1867,6 +1867,7 @@ ocResolve_ELF ( ObjectCode* oc )
 #endif
                 ASSERT(symbol->elf_sym->st_name == 0);
                 ASSERT(symbol->elf_sym->st_value == 0);
+                ASSERT(0x0 != oc->sections[ secno ].start);
                 symbol->addr = oc->sections[ secno ].start;
             }
         }
@@ -1940,6 +1941,7 @@ int ocRunInit_ELF( ObjectCode *oc )
          init_start = (init_t*)init_startC;
          init_end = (init_t*)(init_startC + shdr[i].sh_size);
          for (init = init_start; init < init_end; init++) {
+            ASSERT(0x0 != *init);
             (*init)(argc, argv, envv);
          }
       }


=====================================
rts/linker/SymbolExtras.c
=====================================
@@ -140,7 +140,12 @@ void ocProtectExtras(ObjectCode* oc)
      * non-executable.
      */
   } else if (USE_CONTIGUOUS_MMAP || RtsFlags.MiscFlags.linkerAlwaysPic) {
-    mmapForLinkerMarkExecutable(oc->symbol_extras, sizeof(SymbolExtra) * oc->n_symbol_extras);
+    // XXX   I'm not sure how this is supposed to work.
+    // XXX
+    // XXX   oc->symbol_extras would need to be assigned on page boundaries, and mmaped
+    // XXX   but this is not guaranteed in any form or fashion?
+    // XXX
+    // mmapForLinkerMarkExecutable(oc->symbol_extras, sizeof(SymbolExtra) * oc->n_symbol_extras);
   } else {
     /*
      * The symbol extras were allocated via m32. They will be protected when


=====================================
rts/linker/elf_reloc_aarch64.c
=====================================
@@ -297,7 +297,7 @@ relocateObjectCodeAarch64(ObjectCode * oc) {
                                relTab->sectionHeader->sh_link,
                                ELF64_R_SYM((Elf64_Xword)rel->r_info));
 
-            assert(symbol != NULL);
+            assert(0x0 != symbol);
 
             /* decode implicit addend */
             int64_t addend = decodeAddendAarch64(targetSection, rel);
@@ -324,6 +324,7 @@ relocateObjectCodeAarch64(ObjectCode * oc) {
                                ELF64_R_SYM((Elf64_Xword)rel->r_info));
 
             assert(0x0 != symbol);
+            assert(0x0 != symbol->addr);
 
             /* take explicit addend */
             int64_t addend = rel->r_addend;



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/047ee59e16d54893fd49ef15f9527ddfa9d7757a

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/047ee59e16d54893fd49ef15f9527ddfa9d7757a
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