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X86: Add alloca probing to dynamic alloca on Windows. Fixes PR8424.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116984 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael J. Spencer
2010-10-21 01:41:01 +00:00
parent d6865de2d2
commit e9c253e0bc
4 changed files with 26 additions and 23 deletions
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16
lib/Target/X86/X86InstrCompiler.td
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@@ -94,18 +94,18 @@ def VAARG_64 : I<0, Pseudo,
(X86vaarg64 addr:$ap, imm:$size, imm:$mode, imm:$align)),
(implicit EFLAGS)]>;
// 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.
// Dynamic stack allocation yields a _chkstk or _alloca call for all Windows
// targets. These calls are 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.
let Defs = [EAX, ESP, EFLAGS], Uses = [ESP] in
def MINGW_ALLOCA : I<0, Pseudo, (outs), (ins),
"# dynamic stack allocation",
[(X86MingwAlloca)]>;
def WIN_ALLOCA : I<0, Pseudo, (outs), (ins),
"# dynamic stack allocation",
[(X86WinAlloca)]>;
}