[MC] Make bundle alignment mode setting idempotent and support nested bundles
Summary:
Currently an error is thrown if bundle alignment mode is set more than once
per module (either via the API or the .bundle_align_mode directive). This
change allows setting it multiple times as long as the alignment doesn't
change.
Also nested bundle_lock groups are currently not allowed. This change allows
them, with the effect that the group stays open until all nests are exited,
and if any of the bundle_lock directives has the align_to_end flag, the
group becomes align_to_end.
These changes make the bundle aligment simpler to use in the compiler, and
also better match the corresponding support in GNU as.
Reviewers: jvoung, eliben
Differential Revision: http://reviews.llvm.org/D5801
llvm-svn: 219811
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index bc78a29..85d0c13 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -291,7 +291,9 @@
: Section(&_Section),
Ordinal(~UINT32_C(0)),
Alignment(1),
- BundleLockState(NotBundleLocked), BundleGroupBeforeFirstInst(false),
+ BundleLockState(NotBundleLocked),
+ BundleLockNestingDepth(0),
+ BundleGroupBeforeFirstInst(false),
HasInstructions(false)
{
if (A)
@@ -328,6 +330,25 @@
return IP;
}
+void MCSectionData::setBundleLockState(BundleLockStateType NewState) {
+ if (NewState == NotBundleLocked) {
+ if (BundleLockNestingDepth == 0) {
+ report_fatal_error("Mismatched bundle_lock/unlock directives");
+ }
+ if (--BundleLockNestingDepth == 0) {
+ BundleLockState = NotBundleLocked;
+ }
+ return;
+ }
+
+ // If any of the directives is an align_to_end directive, the whole nested
+ // group is align_to_end. So don't downgrade from align_to_end to just locked.
+ if (BundleLockState != BundleLockedAlignToEnd) {
+ BundleLockState = NewState;
+ }
+ ++BundleLockNestingDepth;
+}
+
/* *** */
MCSymbolData::MCSymbolData() : Symbol(nullptr) {}