Author: [email protected]
Date: Wed Dec 31 01:09:38 2008
New Revision: 1023
Modified:
branches/experimental/toiger/src/codegen-ia32.cc
Log:
Experimental: allow register allocation across if statements and empty
statements.
Review URL: http://codereview.chromium.org/17020
Modified: branches/experimental/toiger/src/codegen-ia32.cc
==============================================================================
--- branches/experimental/toiger/src/codegen-ia32.cc (original)
+++ branches/experimental/toiger/src/codegen-ia32.cc Wed Dec 31 01:09:38
2008
@@ -1490,7 +1490,6 @@
void CodeGenerator::VisitEmptyStatement(EmptyStatement* node) {
ASSERT(!in_spilled_code());
- VirtualFrame::SpilledScope spilled_scope(this);
Comment cmnt(masm_, "// EmptyStatement");
CodeForStatement(node);
// nothing to do
@@ -1499,7 +1498,6 @@
void CodeGenerator::VisitIfStatement(IfStatement* node) {
ASSERT(!in_spilled_code());
- VirtualFrame::SpilledScope spilled_scope(this);
Comment cmnt(masm_, "[ IfStatement");
// Generate different code depending on which parts of the if statement
// are present or not.
@@ -1511,84 +1509,84 @@
if (has_then_stm && has_else_stm) {
JumpTarget then(this);
JumpTarget else_(this);
- // if (cond)
- LoadConditionAndSpill(node->condition(), NOT_INSIDE_TYPEOF,
- &then, &else_, true);
- // An invalid frame here indicates that the code for the condition
- // cannot fall-through, i.e. it caused unconditional jumps to the
- // targets.
+ LoadCondition(node->condition(), NOT_INSIDE_TYPEOF, &then, &else_,
true);
if (has_valid_frame()) {
+ // We have fallen through from the condition (with a value in
cc_reg).
+ // Emit a branch if false around the then block and compile both
+ // blocks.
Branch(false, &else_);
}
- // then
- if (has_valid_frame() || then.is_linked()) {
- // If control flow can reach the then part via fall-through from the
- // test or a branch to the target, compile it.
+ if (then.is_linked()) {
then.Bind();
- VisitAndSpill(node->then_statement());
}
- // A NULL frame here indicates that control did not fall out of the
then
- // statement, it escaped on all branches. In that case, a jump to the
- // exit label would be dead code (and impossible, because we don't have
- // a current virtual frame to set at the exit label).
if (has_valid_frame()) {
+ // We have fallen through from the condition or reached here by a
+ // direct jump to the then target.
+ Visit(node->then_statement());
+ }
+ if (has_valid_frame() && else_.is_linked()) {
+ // We have fallen through from the then block and we need to compile
+ // the else block. Emit an unconditional jump around it.
exit.Jump();
}
- // else
if (else_.is_linked()) {
- // Control flow for if-then-else does not fall-through to the else
- // part, it can only reach here via jump if at all.
else_.Bind();
- VisitAndSpill(node->else_statement());
+ Visit(node->else_statement());
}
} else if (has_then_stm) {
ASSERT(!has_else_stm);
JumpTarget then(this);
- // if (cond)
- LoadConditionAndSpill(node->condition(), NOT_INSIDE_TYPEOF,
- &then, &exit, true);
+ LoadCondition(node->condition(), NOT_INSIDE_TYPEOF, &then, &exit,
true);
if (has_valid_frame()) {
+ // We have fallen through from the condition (with a value in
cc_reg).
+ // Emit a branch if false around the then block.
Branch(false, &exit);
}
- // then
- if (has_valid_frame() || then.is_linked()) {
+ if (then.is_linked()) {
then.Bind();
- VisitAndSpill(node->then_statement());
+ }
+ if (has_valid_frame()) {
+ // We have fallen through from the condition or reached here by a
+ // direct jump to the then target.
+ Visit(node->then_statement());
}
} else if (has_else_stm) {
ASSERT(!has_then_stm);
JumpTarget else_(this);
- // if (!cond)
- LoadConditionAndSpill(node->condition(), NOT_INSIDE_TYPEOF,
- &exit, &else_, true);
+ LoadCondition(node->condition(), NOT_INSIDE_TYPEOF, &exit, &else_,
true);
if (has_valid_frame()) {
+ // We have fallen through from the condition (with a value in
cc_reg).
+ // Emit a branch if true around the else block.
Branch(true, &exit);
}
- // else
- if (has_valid_frame() || else_.is_linked()) {
+ if (else_.is_linked()) {
else_.Bind();
- VisitAndSpill(node->else_statement());
+ }
+ if (has_valid_frame()) {
+ // We have fallen through from the condition or reached here by a
+ // direct jump to the else target.
+ Visit(node->else_statement());
}
} else {
ASSERT(!has_then_stm && !has_else_stm);
- // if (cond)
- LoadConditionAndSpill(node->condition(), NOT_INSIDE_TYPEOF,
- &exit, &exit, false);
+ // We only care about the condition's side effects (not its value or
+ // control flow effect). LoadCondition is called without forcing a
+ // value into cc_reg.
+ LoadCondition(node->condition(), NOT_INSIDE_TYPEOF, &exit, &exit,
false);
if (has_valid_frame()) {
+ // Control flow can fall off the end of the condition. We discard
its
+ // value, which may be in cc_reg or else on top of the virtual frame.
if (has_cc()) {
cc_reg_ = no_condition;
} else {
- // No cc value set up, that means the boolean was pushed.
- // Pop it again, since it is not going to be used.
frame_->Drop();
}
}
}
- // end
if (exit.is_linked()) {
exit.Bind();
}
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