[llvm-commits] [llvm] r166880 - in /llvm/trunk: lib/CodeGen/RegisterCoalescer.cpp test/CodeGen/X86/crash.ll

[Jakob Stoklund Olesen]

Author: stoklund
Date: Sat Oct 27 12:41:27 2012
New Revision: 166880

URL: http://llvm.org/viewvc/llvm-project?rev=166880&view=rev
Log:
Never attempt to join an early-clobber def with a regular kill.

This fixes PR14194.

Modified:
    llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
    llvm/trunk/test/CodeGen/X86/crash.ll

Modified: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp?rev=166880&r1=166879&r2=166880&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp Sat Oct 27 12:41:27 2012
@@ -1492,6 +1492,20 @@
   if ((V.WriteLanes & OtherV.ValidLanes) == 0)
     return CR_Replace;
 
+  // If the other live range is killed by DefMI and the live ranges are still
+  // overlapping, it must be because we're looking at an early clobber def:
+  //
+  //   %dst<def,early-clobber> = ASM %src<kill>
+  //
+  // In this case, it is illegal to merge the two live ranges since the early
+  // clobber def would clobber %src before it was read.
+  if (OtherLRQ.isKill()) {
+    // This case where the def doesn't overlap the kill is handled above.
+    assert(VNI->def.isEarlyClobber() &&
+           "Only early clobber defs can overlap a kill");
+    return CR_Impossible;
+  }
+
   // VNI is clobbering live lanes in OtherVNI, but there is still the
   // possibility that no instructions actually read the clobbered lanes.
   // If we're clobbering all the lanes in OtherVNI, at least one must be read.

Modified: llvm/trunk/test/CodeGen/X86/crash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/crash.ll?rev=166880&r1=166879&r2=166880&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/crash.ll (original)
+++ llvm/trunk/test/CodeGen/X86/crash.ll Sat Oct 27 12:41:27 2012
@@ -580,3 +580,12 @@
 bb29:                                             ; preds = %bb28, %bb26, %bb25, %bb21
   unreachable
 }
+
+define void @pr14194() nounwind uwtable {
+  %tmp = load i64* undef, align 16
+  %tmp1 = trunc i64 %tmp to i32
+  %tmp2 = lshr i64 %tmp, 32
+  %tmp3 = trunc i64 %tmp2 to i32
+  %tmp4 = call { i32, i32 } asm sideeffect "", "=&r,=&r,r,r,0,1,~{dirflag},~{fpsr},~{flags}"(i32 %tmp3, i32 undef, i32 %tmp3, i32 %tmp1) nounwind
+ ret void
+}