Reviewers: Hablich, Benedikt Meurer,
Description:
Use a label-branch in CheckConstPool.
This removes a dependency on the size of the pool. Whilst the size is
checked in debug mode, it is still more robust to use a label.
This should also be cherry-picked to fix 4.4.63.20. (At that time, the
size of the pool was _not_ checked, and was sometimes wrong.)
This partially reverts 879550c, "[arm] Don't call branch_offset within
CheckConstPool." However, branch_offset now only blocks the constant
pool if it is not already blocked.
BUG=
Please review this at https://codereview.chromium.org/1227403006/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+10, -2 lines):
M src/arm/assembler-arm.cc
Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index
96bdf79facedebfecd39c57e2cda0668f1f7c006..6f67a7031d339797aaf913b0f160dfdbdf403d31
100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -1325,7 +1325,8 @@ int Assembler::branch_offset(Label* L) {
// Block the emission of the constant pool, since the branch instruction
must
// be emitted at the pc offset recorded by the label.
- BlockConstPoolFor(1);
+ if (!is_const_pool_blocked()) BlockConstPoolFor(1);
+
return target_pos - (pc_offset() + kPcLoadDelta);
}
@@ -3838,7 +3839,10 @@ void Assembler::CheckConstPool(bool force_emit, bool
require_jump) {
bind(&size_check);
// Emit jump over constant pool if necessary.
- if (require_jump) b(size - kPcLoadDelta);
+ Label after_pool;
+ if (require_jump) {
+ b(&after_pool);
+ }
// Put down constant pool marker "Undefined instruction".
// The data size helps disassembly know what to print.
@@ -3922,6 +3926,10 @@ void Assembler::CheckConstPool(bool force_emit, bool
require_jump) {
RecordComment("]");
DCHECK_EQ(size, SizeOfCodeGeneratedSince(&size_check));
+
+ if (after_pool.is_linked()) {
+ bind(&after_pool);
+ }
}
// Since a constant pool was just emitted, move the check offset forward
by
--
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