all: merge dev.cc (81884b89bd88) into default

With this change, default now contains Go 1.5 work.
Any future bug fixes for Go 1.4 in the compilers or
the runtime will have to be made directly to the
release branch.

1 files changed, 2 insertions, 95 deletions

diff --git a/src/runtime/stack.h b/src/runtime/stack.h
index f97dc4ed8d..0099d05c23 100644
--- a/src/runtime/stack.h
+++ b/src/runtime/stack.h
@@ -2,117 +2,24 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-/*
-Stack layout parameters.
-Included both by runtime (compiled via 6c) and linkers (compiled via gcc).
-
-The per-goroutine g->stackguard is set to point StackGuard bytes
-above the bottom of the stack.  Each function compares its stack
-pointer against g->stackguard to check for overflow.  To cut one
-instruction from the check sequence for functions with tiny frames,
-the stack is allowed to protrude StackSmall bytes below the stack
-guard.  Functions with large frames don't bother with the check and
-always call morestack.  The sequences are (for amd64, others are
-similar):
- 
-	guard = g->stackguard
-	frame = function's stack frame size
-	argsize = size of function arguments (call + return)
-
-	stack frame size <= StackSmall:
-		CMPQ guard, SP
-		JHI 3(PC)
-		MOVQ m->morearg, $(argsize << 32)
-		CALL morestack(SB)
-
-	stack frame size > StackSmall but < StackBig
-		LEAQ (frame-StackSmall)(SP), R0
-		CMPQ guard, R0
-		JHI 3(PC)
-		MOVQ m->morearg, $(argsize << 32)
-		CALL morestack(SB)
-
-	stack frame size >= StackBig:
-		MOVQ m->morearg, $((argsize << 32) | frame)
-		CALL morestack(SB)
-
-The bottom StackGuard - StackSmall bytes are important: there has
-to be enough room to execute functions that refuse to check for
-stack overflow, either because they need to be adjacent to the
-actual caller's frame (deferproc) or because they handle the imminent
-stack overflow (morestack).
-
-For example, deferproc might call malloc, which does one of the
-above checks (without allocating a full frame), which might trigger
-a call to morestack.  This sequence needs to fit in the bottom
-section of the stack.  On amd64, morestack's frame is 40 bytes, and
-deferproc's frame is 56 bytes.  That fits well within the
-StackGuard - StackSmall bytes at the bottom.  
-The linkers explore all possible call traces involving non-splitting
-functions to make sure that this limit cannot be violated.
- */
+// For the linkers. Must match Go definitions.
+// TODO(rsc): Share Go definitions with linkers directly.
 
 enum {
-	// StackSystem is a number of additional bytes to add
-	// to each stack below the usual guard area for OS-specific
-	// purposes like signal handling. Used on Windows and on
-	// Plan 9 because they do not use a separate stack.
 #ifdef GOOS_windows
 	StackSystem = 512 * sizeof(uintptr),
 #else
 #ifdef GOOS_plan9
-	// The size of the note handler frame varies among architectures,
-	// but 512 bytes should be enough for every implementation.
 	StackSystem = 512,
 #else
 	StackSystem = 0,
 #endif	// Plan 9
 #endif	// Windows
 
-	// The minimum size of stack used by Go code
-	StackMin = 2048,
-
-	// The minimum stack size to allocate.
-	// The hackery here rounds FixedStack0 up to a power of 2.
-	FixedStack0 = StackMin + StackSystem,
-	FixedStack1 = FixedStack0 - 1,
-	FixedStack2 = FixedStack1 | (FixedStack1 >> 1),
-	FixedStack3 = FixedStack2 | (FixedStack2 >> 2),
-	FixedStack4 = FixedStack3 | (FixedStack3 >> 4),
-	FixedStack5 = FixedStack4 | (FixedStack4 >> 8),
-	FixedStack6 = FixedStack5 | (FixedStack5 >> 16),
-	FixedStack = FixedStack6 + 1,
-
-	// Functions that need frames bigger than this use an extra
-	// instruction to do the stack split check, to avoid overflow
-	// in case SP - framesize wraps below zero.
-	// This value can be no bigger than the size of the unmapped
-	// space at zero.
 	StackBig = 4096,
-
-	// The stack guard is a pointer this many bytes above the
-	// bottom of the stack.
 	StackGuard = 512 + StackSystem,
-
-	// After a stack split check the SP is allowed to be this
-	// many bytes below the stack guard.  This saves an instruction
-	// in the checking sequence for tiny frames.
 	StackSmall = 128,
-
-	// The maximum number of bytes that a chain of NOSPLIT
-	// functions can use.
 	StackLimit = StackGuard - StackSystem - StackSmall,
 };
 
-// Goroutine preemption request.
-// Stored into g->stackguard0 to cause split stack check failure.
-// Must be greater than any real sp.
-// 0xfffffade in hex.
 #define StackPreempt ((uint64)-1314)
-/*c2go
-enum
-{
-	StackPreempt = -1314,
-};
-*/
-#define StackFork ((uint64)-1234)