[llvm] 0bd4365 - [LiveIntervals] Fix verification of early-clobbered segments

[Jay Foad via llvm-commits]

Author: Jay Foad
Date: 2021-10-05T08:17:56+01:00
New Revision: 0bd4365445e6989be71b23438f7235bb24b9c188

URL: https://github.com/llvm/llvm-project/commit/0bd4365445e6989be71b23438f7235bb24b9c188
DIFF: https://github.com/llvm/llvm-project/commit/0bd4365445e6989be71b23438f7235bb24b9c188.diff

LOG: [LiveIntervals] Fix verification of early-clobbered segments

Enable verification of live intervals immediately after computing them
(when -early-live-intervals is used) and fix a problem that that
provokes: currently the verifier insists that a segment that ends at an
early-clobber slot must be followed by another segment starting at the
same slot. But before TwoAddressInstruction runs, the equivalent
condition is: a segment that ends at an early-clobber slot must have its
last use tied to an early-clobber def. That condition is harder to check
here, so for now just disable this check until tied operands have been
rewritten.

Differential Revision: https://reviews.llvm.org/D111065

Added: 
    

Modified: 
    llvm/lib/CodeGen/MachineVerifier.cpp
    llvm/lib/CodeGen/TargetPassConfig.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index 7295773b5c659..d0aead2d35bd5 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -2944,9 +2944,13 @@ void MachineVerifier::verifyLiveRangeSegment(const LiveRange &LR,
     }
   }
 
-  // A live segment can only end at an early-clobber slot if it is being
-  // redefined by an early-clobber def.
-  if (S.end.isEarlyClobber()) {
+  // After tied operands are rewritten, a live segment can only end at an
+  // early-clobber slot if it is being redefined by an early-clobber def.
+  // TODO: Before tied operands are rewritten, a live segment can only end at an
+  // early-clobber slot if the last use is tied to an early-clobber def.
+  if (MF->getProperties().hasProperty(
+          MachineFunctionProperties::Property::TiedOpsRewritten) &&
+      S.end.isEarlyClobber()) {
     if (I+1 == LR.end() || (I+1)->start != S.end) {
       report("Live segment ending at early clobber slot must be "
              "redefined by an EC def in the same instruction", EndMBB);

diff  --git a/llvm/lib/CodeGen/TargetPassConfig.cpp b/llvm/lib/CodeGen/TargetPassConfig.cpp
index af98386cb7e07..aacba85883535 100644
--- a/llvm/lib/CodeGen/TargetPassConfig.cpp
+++ b/llvm/lib/CodeGen/TargetPassConfig.cpp
@@ -1450,7 +1450,7 @@ void TargetPassConfig::addOptimizedRegAlloc() {
 
   // Eventually, we want to run LiveIntervals before PHI elimination.
   if (EarlyLiveIntervals)
-    addPass(&LiveIntervalsID, false);
+    addPass(&LiveIntervalsID);
 
   addPass(&TwoAddressInstructionPassID, false);
   addPass(&RegisterCoalescerID);