Author: [email protected]
Date: Mon Feb 23 04:05:40 2009
New Revision: 1337
Modified:
branches/bleeding_edge/src/codegen-arm.cc
Log:
Cleanup the ARM code generator for try...catch and try...finally by
clarifying the comments and simplifying code.
Review URL: http://codereview.chromium.org/27047
Modified: branches/bleeding_edge/src/codegen-arm.cc
==============================================================================
--- branches/bleeding_edge/src/codegen-arm.cc (original)
+++ branches/bleeding_edge/src/codegen-arm.cc Mon Feb 23 04:05:40 2009
@@ -1764,7 +1764,8 @@
// Generate code for the statements in the try block.
VisitStatements(node->try_block()->statements());
- frame_->Pop(); // Discard the result.
+ // Discard the code slot from the handler.
+ frame_->Pop();
// Stop the introduced shadowing and count the number of required
unlinks.
// After shadowing stops, the original labels are unshadowed and the
@@ -1776,16 +1777,15 @@
}
// Unlink from try chain.
- // TOS contains code slot
- const int kNextIndex = (StackHandlerConstants::kNextOffset
- + StackHandlerConstants::kAddressDisplacement)
- / kPointerSize;
+ // The code slot has already been discarded, so the next index is
+ // adjusted by 1.
+ const int kNextIndex =
+ (StackHandlerConstants::kNextOffset / kPointerSize) - 1;
__ ldr(r1, frame_->Element(kNextIndex)); // read next_sp
__ mov(r3, Operand(ExternalReference(Top::k_handler_address)));
__ str(r1, MemOperand(r3));
- ASSERT(StackHandlerConstants::kCodeOffset == 0); // first field is code
+ // The code slot has already been dropped from the handler.
frame_->Drop(StackHandlerConstants::kSize / kPointerSize - 1);
- // Code slot popped.
if (nof_unlinks > 0) __ b(&exit);
// Generate unlink code for the (formerly) shadowing labels that have
been
@@ -1802,9 +1802,8 @@
__ ldr(r1, frame_->Element(kNextIndex));
__ str(r1, MemOperand(r3));
- ASSERT(StackHandlerConstants::kCodeOffset == 0); // first field is
code
+ // The code slot has already been dropped from the handler.
frame_->Drop(StackHandlerConstants::kSize / kPointerSize - 1);
- // Code slot popped.
__ b(shadows[i]->original_label());
}
@@ -1891,7 +1890,7 @@
// Unlink from try chain;
__ bind(&unlink);
- frame_->Pop(r0); // Store TOS in r0 across stack manipulation
+ frame_->Pop(r0); // Preserve TOS result in r0 across stack manipulation.
// Reload sp from the top handler, because some statements that we
// break from (eg, for...in) may have left stuff on the stack.
__ mov(r3, Operand(ExternalReference(Top::k_handler_address)));
@@ -1902,8 +1901,11 @@
__ ldr(r1, frame_->Element(kNextIndex));
__ str(r1, MemOperand(r3));
ASSERT(StackHandlerConstants::kCodeOffset == 0); // first field is code
+ // The stack pointer was restored to just below the code slot (the
+ // topmost slot) of the handler, so all but the code slot need to be
+ // dropped.
frame_->Drop(StackHandlerConstants::kSize / kPointerSize - 1);
- // Code slot popped.
+ // Restore result to TOS.
frame_->Push(r0);
// --- Finally block ---
@@ -1932,14 +1934,7 @@
for (int i = 0; i <= nof_escapes; i++) {
if (shadows[i]->is_bound()) {
__ cmp(r2, Operand(Smi::FromInt(JUMPING + i)));
- if (shadows[i]->original_label() != &function_return_) {
- Label next;
- __ b(ne, &next);
- __ b(shadows[i]->original_label());
- __ bind(&next);
- } else {
- __ b(eq, shadows[i]->original_label());
- }
+ __ b(eq, shadows[i]->original_label());
}
}
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