One more coalescer fix wrt deadness propagation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48837 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 50 insertions, 14 deletions

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 8ae36db..aa5cda0 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -554,6 +554,23 @@ void SimpleRegisterCoalescing::ShortenDeadCopyLiveRange(LiveInterval &li,
   }
 }
 
+/// PropagateDeadness - Propagate the dead marker to the instruction which
+/// defines the val#.
+static void PropagateDeadness(LiveInterval &li, MachineInstr *CopyMI,
+                              unsigned &LRStart, LiveIntervals *li_,
+                              const TargetRegisterInfo* tri_) {
+  MachineInstr *DefMI =
+    li_->getInstructionFromIndex(li_->getDefIndex(LRStart));
+  if (DefMI && DefMI != CopyMI) {
+    int DeadIdx = DefMI->findRegisterDefOperandIdx(li.reg, false, tri_);
+    if (DeadIdx != -1) {
+      DefMI->getOperand(DeadIdx).setIsDead();
+      // A dead def should have a single cycle interval.
+      ++LRStart;
+    }
+  }
+}
+
 /// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially
 /// extended by a dead copy. Mark the last use (if any) of the val# as kill
 /// as ends the live range there. If there isn't another use, then this
@@ -613,23 +630,14 @@ SimpleRegisterCoalescing::ShortenDeadCopySrcLiveRange(LiveInterval &li,
       // Live-in to the function but dead. Remove it from entry live-in set.
       mf_->begin()->removeLiveIn(li.reg);
     }
-    removeRange(li, LR->start, LR->end, li_, tri_);
     // FIXME: Shorten intervals in BBs that reaches this BB.
-  } else {
-    // Not livein into BB.
-    MachineInstr *DefMI =
-      li_->getInstructionFromIndex(li_->getDefIndex(RemoveStart));
-    if (DefMI && DefMI != CopyMI) {
-      int DeadIdx = DefMI->findRegisterDefOperandIdx(li.reg, false, tri_);
-      if (DeadIdx != -1) {
-        DefMI->getOperand(DeadIdx).setIsDead();
-        // A dead def should have a single cycle interval.
-        ++RemoveStart;
-      }
-    }
-    removeRange(li, RemoveStart, LR->end, li_, tri_);
   }
 
+  if (LR->valno->def == RemoveStart)
+    // If the def MI defines the val#, propagate the dead marker.
+    PropagateDeadness(li, CopyMI, RemoveStart, li_, tri_);
+
+  removeRange(li, RemoveStart, LR->end, li_, tri_);
   removeIntervalIfEmpty(li, li_, tri_);
 }
 
diff --git a/test/CodeGen/PowerPC/2008-03-26-CoalescerBug.ll b/test/CodeGen/PowerPC/2008-03-26-CoalescerBug.ll
new file mode 100644
index 0000000..0b748d2
--- /dev/null
+++ b/test/CodeGen/PowerPC/2008-03-26-CoalescerBug.ll
@@ -0,0 +1,28 @@
+; RUN: llvm-as < %s | llc -mtriple=powerpc-apple-darwin
+
+define i32 @t(i64 %byteStart, i32 %activeIndex) nounwind  {
+entry:
+	%tmp50 = load i32* null, align 4		; <i32> [#uses=1]
+	%tmp5051 = zext i32 %tmp50 to i64		; <i64> [#uses=3]
+	%tmp53 = udiv i64 %byteStart, %tmp5051		; <i64> [#uses=1]
+	%tmp5354 = trunc i64 %tmp53 to i32		; <i32> [#uses=1]
+	%tmp62 = urem i64 %byteStart, %tmp5051		; <i64> [#uses=1]
+	%tmp94 = add i32 0, 1		; <i32> [#uses=1]
+	%tmp100 = urem i32 %tmp94, 0		; <i32> [#uses=2]
+	%tmp108 = add i32 0, %activeIndex		; <i32> [#uses=1]
+	%tmp110 = sub i32 %tmp108, 0		; <i32> [#uses=1]
+	%tmp112 = urem i32 %tmp110, 0		; <i32> [#uses=2]
+	%tmp122 = icmp ult i32 %tmp112, %tmp100		; <i1> [#uses=1]
+	%iftmp.175.0 = select i1 %tmp122, i32 %tmp112, i32 %tmp100		; <i32> [#uses=1]
+	%tmp119 = add i32 %tmp5354, 0		; <i32> [#uses=1]
+	%tmp131 = add i32 %tmp119, %iftmp.175.0		; <i32> [#uses=1]
+	%tmp131132 = zext i32 %tmp131 to i64		; <i64> [#uses=1]
+	%tmp147 = mul i64 %tmp131132, %tmp5051		; <i64> [#uses=1]
+	br i1 false, label %bb164, label %bb190
+bb164:		; preds = %entry
+	%tmp171172 = and i64 %tmp62, 4294967295		; <i64> [#uses=1]
+	%tmp173 = add i64 %tmp171172, %tmp147		; <i64> [#uses=0]
+	ret i32 0
+bb190:		; preds = %entry
+	ret i32 0
+}