diff options
| -rw-r--r-- | lib/Target/X86/X86InstrInfo.td | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td index 9953b052cf..8a6ff54c77 100644 --- a/lib/Target/X86/X86InstrInfo.td +++ b/lib/Target/X86/X86InstrInfo.td @@ -533,8 +533,16 @@ def VASTART_SAVE_XMM_REGS : I<0, Pseudo, imm:$regsavefi, imm:$offset)]>; +// Dynamic stack allocation yields _alloca call for Cygwin/Mingw targets. Calls +// to _alloca is needed to probe the stack when allocating more than 4k bytes in +// one go. Touching the stack at 4K increments is necessary to ensure that the +// guard pages used by the OS virtual memory manager are allocated in correct +// sequence. +// The main point of having separate instruction are extra unmodelled effects +// (compared to ordinary calls) like stack pointer change. + def MINGW_ALLOCA : I<0, Pseudo, (outs), (ins), - "call __alloca", + "# dynamic stack allocation", [(X86MingwAlloca)]>; } |