[llvm-commits] [llvm] r135885 - in /llvm/trunk: lib/CodeGen/SplitKit.cpp test/CodeGen/X86/crash.ll

[Jakob Stoklund Olesen]

Author: stoklund
Date: Sun Jul 24 15:23:50 2011
New Revision: 135885

URL: http://llvm.org/viewvc/llvm-project?rev=135885&view=rev
Log:
Correctly handle <undef> tied uses when rewriting after a split.

This fixes PR10463. A two-address instruction with an <undef> use
operand was incorrectly rewritten so the def and use no longer used the
same register, violating the tie constraint.

Fix this by always rewriting <undef> operands with the register a def
operand would use.

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

Modified: llvm/trunk/lib/CodeGen/SplitKit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.cpp?rev=135885&r1=135884&r2=135885&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.cpp (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.cpp Sun Jul 24 15:23:50 2011
@@ -938,15 +938,11 @@
       continue;
     }
 
-    // <undef> operands don't really read the register, so just assign them to
-    // the complement.
-    if (MO.isUse() && MO.isUndef()) {
-      MO.setReg(Edit->get(0)->reg);
-      continue;
-    }
-
+    // <undef> operands don't really read the register, so it doesn't matter
+    // which register we choose.  When the use operand is tied to a def, we must
+    // use the same register as the def, so just do that always.
     SlotIndex Idx = LIS.getInstructionIndex(MI);
-    if (MO.isDef())
+    if (MO.isDef() || MO.isUndef())
       Idx = MO.isEarlyClobber() ? Idx.getUseIndex() : Idx.getDefIndex();
 
     // Rewrite to the mapped register at Idx.

Modified: llvm/trunk/test/CodeGen/X86/crash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/crash.ll?rev=135885&r1=135884&r2=135885&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/crash.ll (original)
+++ llvm/trunk/test/CodeGen/X86/crash.ll Sun Jul 24 15:23:50 2011
@@ -316,3 +316,28 @@
 declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
 
 declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind
+
+; PR10463
+; Spilling a virtual register with <undef> uses.
+define void @autogen_239_1000() {
+BB:
+    %Shuff = shufflevector <8 x double> undef, <8 x double> undef, <8 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 undef, i32 undef>
+    br label %CF
+
+CF:
+    %B16 = frem <8 x double> zeroinitializer, %Shuff
+    %E19 = extractelement <8 x double> %Shuff, i32 5
+    br i1 undef, label %CF, label %CF75
+
+CF75:
+    br i1 undef, label %CF75, label %CF76
+
+CF76:
+    store double %E19, double* undef
+    br i1 undef, label %CF76, label %CF77
+
+CF77:
+    %B55 = fmul <8 x double> %B16, undef
+    br label %CF77
+}
+