Magnus pushed to branch wip/mangoiv/ghc-9.12-bp at Glasgow Haskell Compiler / GHC Commits: 2aacc599 by Andreas Klebinger at 2026-05-20T11:51:11+02:00 Fix missing profiling header for origin_thunk frame. Fixes #27007 (cherry picked from commit 63ae8eb38c54eaba77949b048a3621a5f4ca76e3) - - - - - 0acea5fa by Luite Stegeman at 2026-05-20T11:51:13+02:00 bytecode: Carefully SLIDE off the end of a stack chunk The SLIDE bytecode instruction was not checking for stack chunk boundaries and could corrupt the stack underflow frame, leading to crashes. We add a check to use safe writes if we cross the chunk boundary and also handle stack underflow if Sp is advanced past the underflow frame. fix #27001 (cherry picked from commit 72b20fc0ad4b6ad12c67f686af5cb42700656886) - - - - - b2e91dc8 by Andreas Klebinger at 2026-05-20T11:51:13+02:00 Configure: Fix check for --target support in stage0 CC The check FP_PROG_CC_LINKER_TARGET used $CC unconditionally to check for --target support. However this fails for the stage0 config where the C compiler used is not $CC but $CC_STAGE0. Since we already pass the compiler under test into the macro I simply changed it to use that instead. Fixes #26999 (cherry picked from commit 43638643adbe999de8d2288a40bdd15c602f6481) - - - - - 682654f0 by Ian Duncan at 2026-05-20T11:51:14+02:00 AArch64: fix MOVK regUsageOfInstr to mark dst as both read and written MOVK (move with keep) modifies only a 16-bit slice of the destination register, so the destination is both read and written. The register allocator must know this to avoid clobbering live values. Update regUsageOfInstr to list the destination in both src and dst sets. No regression test: triggering the misallocation requires specific register pressure around a MOVK sequence, which is difficult to reliably provoke from Haskell source. (cherry picked from commit 2823b03966e495581f4695f07649c5885306b656) - - - - - a50fabdf by Zubin Duggal at 2026-05-20T11:51:14+02:00 compiler/ffi: Collapse void pointer chains in capi wrappers New gcc/clang treat -Wincompatible-pointer-types as an error by default. Since C only allows implicit conversion from void*, not void**, capi wrappers for functions taking e.g. abstract** would fail to compile when the Haskell type Ptr (Ptr Abstract) was naively translated to void**. Collapse nested void pointers to a single void* when the pointee type has no known C representation. Fixes #26852 (cherry picked from commit 80e2dd4f084eff9cc857b31daf9ea2e9e460c727) - - - - - b62022a9 by Zubin Duggal at 2026-05-20T11:51:14+02:00 hadrian: Don't include the package hash in the haddock directory Since GHC 9.8 and hash_unit_ids, haddock urls have looked like`ghc-9.10.3/doc/html/libraries/base-4.20.2.0-39f9/**/*.html` The inclusion of the hash makes it hard for downstream non-boot packages to properly link to these files, as the hash is not part of a standard cabal substitution. Since we only build one version of each package, we don't need the hash to disambiguate anything, we can just remove it. Fixes #26635 (cherry picked from commit 07267f79d91169f474cacc8bcd38d76a6e97887d) - - - - - 0f95ad43 by ARATA Mizuki at 2026-05-20T11:51:14+02:00 rts: Align stack to 64-byte boundary in StgRun on x86 When LLVM spills AVX/AVX-512 vector registers to the stack, it requires 32-byte (__m256) or 64-byte (__m512) alignment. If the stack is not sufficiently aligned, LLVM inserts a realignment prologue that reserves %rbp as a frame pointer, conflicting with GHC's use of %rbp as an STG callee-saved register and breaking the tail-call-based calling convention. Previously, GHC worked around this by lying to LLVM about the stack alignment and rewriting aligned vector loads/stores (VMOVDQA, VMOVAPS) to unaligned ones (VMOVDQU, VMOVUPS) in the LLVM Mangler. This had two problems: - It did not extend to AVX-512, which requires 64-byte alignment. (#26595) - When Haskell calls a C function that takes __m256/__m512 arguments on the stack, the callee requires genuine alignment, which could cause a segfault. (#26822) This patch genuinely aligns the stack to 64 bytes in StgRun by saving the original stack pointer before alignment and restoring it in StgReturn. We now unconditionally advertise 64-byte stack alignment to LLVM for all x86 targets, making rewriteAVX in the LLVM Mangler unnecessary. STG_RUN_STACK_FRAME_SIZE is increased from 48 to 56 bytes on non-Windows x86-64 to store the saved stack pointer. Closes #26595 and #26822 Co-Authored-By: Claude Opus 4.5 (cherry picked from commit a5ec467ee3d4e77c026437a545981269acde3434) - - - - - 6726c914 by Wen Kokke at 2026-05-20T11:51:14+02:00 Fix race condition between flushEventLog and start/endEventLogging. This commit changes `flushEventLog` to acquire/release the `state_change` mutex to prevent interleaving with `startEventLogging` and `endEventLogging`. In the current RTS, `flushEventLog` _does not_ acquire this mutex, which may lead to eventlog corruption on the following interleaving: - `startEventLogging` writes the new `EventLogWriter` to `event_log_writer`. - `flushEventLog` flushes some events to `event_log_writer`. - `startEventLogging` writes the eventlog header to `event_log_writer`. This causes the eventlog to be written out in an unreadable state, with one or more events preceding the eventlog header. This commit renames the old function to `flushEventLog_` and defines `flushEventLog` simply as: ```c void flushEventLog(Capability **cap USED_IF_THREADS) { ACQUIRE_LOCK(&state_change_mutex); flushEventLog_(cap); RELEASE_LOCK(&state_change_mutex); } ``` The old function is still needed internally within the compilation unit, where it is used in `endEventLogging` in a context where the `state_change` mutex has already been acquired. I've chosen to mark `flushEventLog_` as static and let other uses of `flushEventLog` within the RTS refer to the new version. There is one use in `hs_init_ghc` via `flushTrace`, where the new locking behaviour should be harmless, and one use in `handle_tick`, which I believe was likely vulnerable to the same race condition, so the new locking behaviour is desirable. I have not added a test. The behaviour is highly non-deterministic and requires a program that concurrently calls `flushEventLog` and `startEventLogging`/`endEventLogging`. I encountered the issue while developing `eventlog-socket` and within that context have verified that my patch likely addresses the issue: a test that used to fail within the first dozen or so runs now has been running on repeat for several hours. (cherry picked from commit 3d6492ce311611707e80b2594103ddbe93fc6c76) - - - - - dbcd6032 by Luite Stegeman at 2026-05-20T11:51:14+02:00 Windows: remove StgAsyncIOResult and fix crash/leaks In stg_block_async{_void}, a stack slot was reserved for an StgAsyncIOResult. This slot would be filled by the IO manager upon completion of the async call. However, if the blocked thread was interrupted by an async exception, we would end up in an invalid state: - If the blocked computation was never re-entered, the StgAsyncIOResult would never be freed. - If the blocked computation was re-entered, the thread would find an unitialized stack slot for the StgAsyncIOResult, leading to a crash reading its fields, or freeing the pointer. We fix this by removing the StgAsyncIOResult altogether and writing the result directly to the stack. Fixes #26341 (cherry picked from commit fcf092dda534cc38637d1f7920aa0dae58fe5273) - - - - - 7bc3cd73 by mangoiv at 2026-05-20T11:51:14+02:00 rts: cast Sp_plusW to StgPtr to appease gcc - - - - - d93c4511 by mangoiv at 2026-05-20T11:51:14+02:00 rts: disable out of bounds array warning for sometimes inlined rts function - - - - - 48 changed files: - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/CmmToLlvm.hs - compiler/GHC/CmmToLlvm/Config.hs - compiler/GHC/CmmToLlvm/Mangler.hs - compiler/GHC/Driver/Config/CmmToLlvm.hs - compiler/GHC/HsToCore/Foreign/C.hs - hadrian/bindist/Makefile - hadrian/src/CommandLine.hs - hadrian/src/Context.hs - hadrian/src/Settings/Builders/Cabal.hs - m4/fp_prog_cc_linker_target.m4 - rts/HeapStackCheck.cmm - rts/IOManager.c - rts/Interpreter.c - rts/PrimOps.cmm - rts/RtsSymbols.c - rts/StgCRun.c - rts/StgMiscClosures.cmm - rts/Threads.c - rts/eventlog/EventLog.c - rts/include/rts/Constants.h - rts/include/rts/storage/ClosureMacros.h - rts/include/rts/storage/TSO.h - rts/include/stg/MiscClosures.h - rts/win32/AsyncMIO.c - rts/win32/AsyncMIO.h - + testsuite/tests/bytecode/T27001.hs - + testsuite/tests/bytecode/T27001.stdout - testsuite/tests/bytecode/all.T - + testsuite/tests/concurrent/should_run/T26341.hs - + testsuite/tests/concurrent/should_run/T26341.stdout - + testsuite/tests/concurrent/should_run/T26341a.hs - + testsuite/tests/concurrent/should_run/T26341a.stdout - + testsuite/tests/concurrent/should_run/T26341b.hs - + testsuite/tests/concurrent/should_run/T26341b.stdout - testsuite/tests/concurrent/should_run/all.T - + testsuite/tests/ffi/should_compile/T26852.h - + testsuite/tests/ffi/should_compile/T26852.hs - + testsuite/tests/ffi/should_compile/T26852.stderr - testsuite/tests/ffi/should_compile/all.T - + testsuite/tests/simd/should_run/StackAlignment32.hs - + testsuite/tests/simd/should_run/StackAlignment32.stdout - + testsuite/tests/simd/should_run/StackAlignment32_main.c - + testsuite/tests/simd/should_run/StackAlignment64.hs - + testsuite/tests/simd/should_run/StackAlignment64.stdout - + testsuite/tests/simd/should_run/StackAlignment64_main.c - testsuite/tests/simd/should_run/all.T - utils/deriveConstants/Main.hs The diff was not included because it is too large. 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