From 76a4d58998ca41d04f03d21afe0257c36d9ce303 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Thu, 17 Jul 2008 19:48:53 +0000
Subject: [PATCH] Subreg live interval valno may not have a corresponding def
 machineinstr since it's less precise.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53734 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SimpleRegisterCoalescing.cpp      |  2 +-
 test/CodeGen/X86/2008-07-16-CoalescerCrash.ll | 34 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 test/CodeGen/X86/2008-07-16-CoalescerCrash.ll

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index bc833633ed2..5b7f55dfc9a 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -1327,7 +1327,7 @@ bool SimpleRegisterCoalescing::RangeIsDefinedByCopyFromReg(LiveInterval &li,
     // Re-compute it.
     MachineInstr *DefMI = li_->getInstructionFromIndex(LR->start);
     unsigned SrcReg, DstReg;
-    if (tii_->isMoveInstr(*DefMI, SrcReg, DstReg) &&
+    if (DefMI && tii_->isMoveInstr(*DefMI, SrcReg, DstReg) &&
         DstReg == li.reg && SrcReg == Reg) {
       // Cache computed info.
       LR->valno->def  = LR->start;
diff --git a/test/CodeGen/X86/2008-07-16-CoalescerCrash.ll b/test/CodeGen/X86/2008-07-16-CoalescerCrash.ll
new file mode 100644
index 00000000000..aa9ee507f80
--- /dev/null
+++ b/test/CodeGen/X86/2008-07-16-CoalescerCrash.ll
@@ -0,0 +1,34 @@
+; RUN: llvm-as < %s | llc -mtriple=x86_64-apple-darwin
+
+	%struct.SV = type { i8*, i64, i64 }
+@"\01LC25" = external constant [8 x i8]		; <[8 x i8]*> [#uses=1]
+
+declare void @Perl_sv_catpvf(%struct.SV*, i8*, ...) nounwind 
+
+declare fastcc i64 @Perl_utf8n_to_uvuni(i8*, i64, i64*, i64) nounwind 
+
+define fastcc i8* @Perl_pv_uni_display(%struct.SV* %dsv, i8* %spv, i64 %len, i64 %pvlim, i64 %flags) nounwind  {
+entry:
+	br i1 false, label %bb, label %bb40
+
+bb:		; preds = %entry
+	tail call fastcc i64 @Perl_utf8n_to_uvuni( i8* null, i64 13, i64* null, i64 255 ) nounwind 		; <i64>:0 [#uses=1]
+	br i1 false, label %bb6, label %bb33
+
+bb6:		; preds = %bb
+	br i1 false, label %bb30, label %bb31
+
+bb30:		; preds = %bb6
+	unreachable
+
+bb31:		; preds = %bb6
+	icmp eq i8 0, 0		; <i1>:1 [#uses=0]
+	br label %bb33
+
+bb33:		; preds = %bb31, %bb
+	tail call void (%struct.SV*, i8*, ...)* @Perl_sv_catpvf( %struct.SV* %dsv, i8* getelementptr ([8 x i8]* @"\01LC25", i32 0, i64 0), i64 %0 ) nounwind 
+	unreachable
+
+bb40:		; preds = %entry
+	ret i8* null
+}