Yet another nasty spiller bug.

%ecx = op
store %cl<kill>, (addr)
(addr) = op %al

It's not safe to unfold the last operand and eliminate store even though %cl is marked kill. It's a sub-register use which means one of its super-register(s) may be used below.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50794 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 56 insertions, 14 deletions

diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 6a34269cea..fe8b6a5a63 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -1465,20 +1465,25 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
           // the value and there isn't an earlier def that has already clobbered
           // the physreg.
           if (PhysReg &&
-              !TII->isStoreToStackSlot(&MI, SS) && // Not profitable!
-              DeadStore->killsRegister(PhysReg) &&
-              TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true, NewMIs)) {
-            MBB.insert(MII, NewMIs[0]);
-            NewStore = NewMIs[1];
-            MBB.insert(MII, NewStore);
-            VRM.addSpillSlotUse(SS, NewStore);
-            VRM.RemoveMachineInstrFromMaps(&MI);
-            MBB.erase(&MI);
-            Erased = true;
-            --NextMII;
-            --NextMII;  // backtrack to the unfolded instruction.
-            BackTracked = true;
-            isDead = true;
+              !TII->isStoreToStackSlot(&MI, SS)) { // Not profitable!
+            MachineOperand *KillOpnd =
+              DeadStore->findRegisterUseOperand(PhysReg, true);
+            // Note, if the store is storing a sub-register, it's possible the
+            // super-register is needed below.
+            if (KillOpnd && !KillOpnd->getSubReg() &&
+                TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true,NewMIs)){
+              MBB.insert(MII, NewMIs[0]);
+              NewStore = NewMIs[1];
+              MBB.insert(MII, NewStore);
+              VRM.addSpillSlotUse(SS, NewStore);
+              VRM.RemoveMachineInstrFromMaps(&MI);
+              MBB.erase(&MI);
+              Erased = true;
+              --NextMII;
+              --NextMII;  // backtrack to the unfolded instruction.
+              BackTracked = true;
+              isDead = true;
+            }
           }
         }
 
diff --git a/test/CodeGen/X86/2008-05-06-SpillerBug.ll b/test/CodeGen/X86/2008-05-06-SpillerBug.ll
new file mode 100644
index 0000000000..19231e9de8
--- /dev/null
+++ b/test/CodeGen/X86/2008-05-06-SpillerBug.ll
@@ -0,0 +1,37 @@
+; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin -relocation-model=pic -disable-fp-elim | grep addb | grep ebp
+
+	%struct.rc4_state = type { i32, i32, [256 x i32] }
+@.str1 = internal constant [65 x i8] c"m[%d] = 0x%02x, m[%d] = 0x%02x, 0x%02x, k = %d, key[k] = 0x%02x\0A\00"		; <[65 x i8]*> [#uses=1]
+@keys = internal constant [7 x [30 x i8]] [ [30 x i8] c"\08\01#Eg\89\AB\CD\EF\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", [30 x i8] c"\08\01#Eg\89\AB\CD\EF\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", [30 x i8] c"\08\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", [30 x i8] c"\04\EF\01#E\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", [30 x i8] c"\08\01#Eg\89\AB\CD\EF\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", [30 x i8] c"\04\EF\01#E\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", [30 x i8] zeroinitializer ]		; <[7 x [30 x i8]]*> [#uses=1]
+
+declare i32 @printf(i8*, ...) nounwind 
+
+define i32 @main(i32 %argc, i8** %argv) nounwind  {
+entry:
+	br label %bb25
+
+bb25:		; preds = %bb25, %entry
+	br i1 false, label %bb.i, label %bb25
+
+bb.i:		; preds = %bb.i, %bb25
+	br i1 false, label %bb21.i, label %bb.i
+
+bb21.i:		; preds = %bb21.i, %bb.i
+	%k.0.reg2mem.0.i = phi i32 [ %k.1.i, %bb21.i ], [ 0, %bb.i ]		; <i32> [#uses=2]
+	%j.0.reg2mem.0.i = phi i8 [ %tmp35.i, %bb21.i ], [ 0, %bb.i ]		; <i8> [#uses=1]
+	%tmp25.i = load i32* null, align 4		; <i32> [#uses=4]
+	%tmp2829.i = trunc i32 %tmp25.i to i8		; <i8> [#uses=1]
+	%.sum = add i32 %k.0.reg2mem.0.i, 1		; <i32> [#uses=3]
+	%tmp33.i = getelementptr [7 x [30 x i8]]* @keys, i32 0, i32 0, i32 %.sum		; <i8*> [#uses=1]
+	%tmp34.i = load i8* %tmp33.i, align 1		; <i8> [#uses=1]
+	%tmp30.i = add i8 %tmp2829.i, %j.0.reg2mem.0.i		; <i8> [#uses=1]
+	%tmp35.i = add i8 %tmp30.i, %tmp34.i		; <i8> [#uses=2]
+	%tmp3536.i = zext i8 %tmp35.i to i32		; <i32> [#uses=2]
+	%tmp39.i = getelementptr %struct.rc4_state* null, i32 0, i32 2, i32 %tmp3536.i		; <i32*> [#uses=1]
+	store i32 %tmp25.i, i32* %tmp39.i, align 4
+	%tmp60.i = load i32* null, align 4		; <i32> [#uses=1]
+	%tmp65.i = call i32 (i8*, ...)* @printf( i8* getelementptr ([65 x i8]* @.str1, i32 0, i32 0), i32 0, i32 %tmp60.i, i32 %tmp3536.i, i32 %tmp25.i, i32 %tmp25.i, i32 %k.0.reg2mem.0.i, i32 0 ) nounwind 		; <i32> [#uses=0]
+	%tmp70.i = icmp slt i32 %.sum, 8		; <i1> [#uses=1]
+	%k.1.i = select i1 %tmp70.i, i32 %.sum, i32 0		; <i32> [#uses=1]
+	br label %bb21.i
+}