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Bug 932768 - Remove vestigial decompiler hacks from BytecodeEmitter. r=jwalden

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This commit is contained in:
Andy Wingo 2013-11-18 16:53:58 +01:00
parent 829b56ffef
commit 67c63f72fb
3 changed files with 18 additions and 37 deletions
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52
js/src/frontend/BytecodeEmitter.cpp
View File

@ -2516,7 +2516,7 @@ EmitSwitch(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
* If we didn't have an explicit default (which could fall in between
* cases, preventing us from fusing this SetSrcNoteOffset with the call
* in the loop above), link the last case to the implicit default for
* the decompiler.
* the benefit of IonBuilder.
*/
if (!hasDefault &&
caseNoteIndex >= 0 &&
@ -2644,7 +2644,7 @@ bool
frontend::EmitFunctionScript(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *body)
{
/*
* The decompiler has assumptions about what may occur immediately after
* IonBuilder has assumptions about what may occur immediately after
* script->main (e.g., in the case of destructuring params). Thus, put the
* following ops into the range [script->code, script->main). Note:
* execution starts from script->code, so this has no semantic effect.
@ -2994,12 +2994,6 @@ EmitDestructuringOpsHelper(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode
JS_ASSERT(pn->isKind(PNK_ARRAY) || pn->isKind(PNK_OBJECT));
#endif
if (pn->pn_count == 0) {
/* Emit a DUP;POP sequence for the decompiler. */
if (Emit1(cx, bce, JSOP_DUP) < 0 || Emit1(cx, bce, JSOP_POP) < 0)
return false;
}
index = 0;
for (pn2 = pn->pn_head; pn2; pn2 = pn2->pn_next) {
/* Duplicate the value being destructured to use as a reference base. */
@ -3067,13 +3061,13 @@ EmitDestructuringOpsHelper(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode
if (emitOption == PushInitialValues) {
/*
* After '[x,y]' in 'let ([[x,y], z] = o)', the stack is
* | to-be-decompiled-value | x | y |
* | to-be-destructured-value | x | y |
* The goal is:
* | x | y | z |
* so emit a pick to produce the intermediate state
* | x | y | to-be-decompiled-value |
* | x | y | to-be-destructured-value |
* before destructuring z. This gives the loop invariant that
* the to-be-compiled-value is always on top of the stack.
* the to-be-destructured-value is always on top of the stack.
*/
JS_ASSERT((bce->stackDepth - bce->stackDepth) >= -1);
unsigned pickDistance = (unsigned)((bce->stackDepth + 1) - depthBefore);
@ -3093,7 +3087,7 @@ EmitDestructuringOpsHelper(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode
if (emitOption == PushInitialValues) {
/*
* Per the above loop invariant, to-be-decompiled-value is at the top
* Per the above loop invariant, to-be-destructured-value is at the top
* of the stack. To achieve the post-condition, pop it.
*/
if (Emit1(cx, bce, JSOP_POP) < 0)
@ -3834,14 +3828,7 @@ EmitCatch(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
}
/* Emit the catch body. */
if (!EmitTree(cx, bce, pn->pn_kid3))
return false;
/*
* Annotate the JSOP_LEAVEBLOCK that will be emitted as we unwind via
* our PNK_LEXICALSCOPE parent, so the decompiler knows to pop.
*/
return NewSrcNote(cx, bce, SRC_CATCH) >= 0;
return EmitTree(cx, bce, pn->pn_kid3);
}
/*
@ -3946,9 +3933,7 @@ EmitTry(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
/*
* Move exception back to cx->exception to prepare for
* the next catch. We hide [throwing] from the decompiler
* since it compensates for the hidden JSOP_DUP at the
* start of the previous guarded catch.
* the next catch.
*/
if (Emit1(cx, bce, JSOP_THROWING) < 0)
return false;
@ -4534,9 +4519,7 @@ EmitForIn(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn, ptrdiff_t t
/*
* Emit code to get the next enumeration value and assign it to the
* left hand side. The JSOP_POP after this assignment is annotated
* so that the decompiler can distinguish 'for (x in y)' from
* 'for (var x in y)'.
* left hand side.
*/
if (Emit1(cx, bce, JSOP_ITERNEXT) < 0)
return false;
@ -4610,7 +4593,8 @@ EmitNormalFor(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn, ptrdiff
JSOp op = JSOP_POP;
ParseNode *pn3 = forHead->pn_kid1;
if (!pn3) {
/* No initializer: emit an annotated nop for the decompiler. */
// No initializer, but emit a nop so that there's somewhere to put the
// SRC_FOR annotation that IonBuilder will look for.
op = JSOP_NOP;
} else {
bce->emittingForInit = true;
@ -4631,7 +4615,7 @@ EmitNormalFor(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn, ptrdiff
* Check whether a destructuring-initialized var decl
* was optimized to a group assignment. If so, we do
* not need to emit a pop below, so switch to a nop,
* just for the decompiler.
* just for IonBuilder.
*/
JS_ASSERT(pn3->isArity(PN_LIST) || pn3->isArity(PN_BINARY));
if (pn3->pn_xflags & PNX_GROUPINIT)
@ -4700,7 +4684,7 @@ EmitNormalFor(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn, ptrdiff
if (op == JSOP_POP && !EmitTree(cx, bce, pn3))
return false;
/* Always emit the POP or NOP, to help the decompiler. */
/* Always emit the POP or NOP to help IonBuilder. */
if (Emit1(cx, bce, op) < 0)
return false;
@ -4905,7 +4889,7 @@ EmitFunc(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
static bool
EmitDo(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
{
/* Emit an annotated nop so we know to decompile a 'do' keyword. */
/* Emit an annotated nop so IonBuilder can recognize the 'do' loop. */
ptrdiff_t noteIndex = NewSrcNote(cx, bce, SRC_WHILE);
if (noteIndex < 0 || Emit1(cx, bce, JSOP_NOP) < 0)
return false;
@ -4939,11 +4923,6 @@ EmitDo(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
if (!EmitTree(cx, bce, pn->pn_right))
return false;
/*
* Since we use JSOP_IFNE for other purposes as well as for do-while
* loops, we must store 1 + (beq - top) in the SRC_WHILE note offset,
* and the decompiler must get that delta and decompile recursively.
*/
ptrdiff_t beq = EmitJump(cx, bce, JSOP_IFNE, top - bce->offset());
if (beq < 0)
return false;
@ -4952,6 +4931,9 @@ EmitDo(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
return false;
/*
* Update the annotations with the update and back edge positions, for
* IonBuilder.
*
* Be careful: We must set noteIndex2 before noteIndex in case the noteIndex
* note gets bigger.
*/

2
js/src/frontend/SourceNotes.h
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@ -59,13 +59,13 @@ namespace js {
M(SRC_NEXTCASE, "nextcase", 1) /* Distance forward from one CASE in a CONDSWITCH to \
the next. */ \
M(SRC_ASSIGNOP, "assignop", 0) /* += or another assign-op follows. */ \
M(SRC_CATCH, "catch", 0) /* Catch block has guard. */ \
M(SRC_TRY, "try", 1) /* JSOP_TRY, offset points to goto at the end of the \
try block. */ \
/* All notes below here are "gettable". See SN_IS_GETTABLE below. */ \
M(SRC_COLSPAN, "colspan", 1) /* Number of columns this opcode spans. */ \
M(SRC_NEWLINE, "newline", 0) /* Bytecode follows a source newline. */ \
M(SRC_SETLINE, "setline", 1) /* A file-absolute source line number note. */ \
M(SRC_UNUSED20, "unused20", 0) /* Unused. */ \
M(SRC_UNUSED21, "unused21", 0) /* Unused. */ \
M(SRC_UNUSED22, "unused22", 0) /* Unused. */ \
M(SRC_UNUSED23, "unused23", 0) /* Unused. */ \

1
js/src/shell/js.cpp
View File

@ -1709,7 +1709,6 @@ SrcNotes(JSContext *cx, HandleScript script, Sprinter *sp)
case SRC_BREAK2LABEL:
case SRC_SWITCHBREAK:
case SRC_ASSIGNOP:
case SRC_CATCH:
case SRC_XDELTA:
break;