Fix an issue where the two-address conversion pass incorrectly rewrites untied

operands to an early clobber register. This fixes <rdar://problem/9566076>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132738 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 52ea87231ccd3c95379ef249862c10f36f0adbd1..f54d879759ff01632050eefe1b0029732e3fdad2 100644 (file)
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1125,6 +1125,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
             break; // The tied operands have been eliminated.
         }
 
+        bool IsEarlyClobber = false;
         bool RemovedKillFlag = false;
         bool AllUsesCopied = true;
         unsigned LastCopiedReg = 0;
@@ -1132,7 +1133,11 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
         for (unsigned tpi = 0, tpe = TiedPairs.size(); tpi != tpe; ++tpi) {
           unsigned SrcIdx = TiedPairs[tpi].first;
           unsigned DstIdx = TiedPairs[tpi].second;
-          unsigned regA = mi->getOperand(DstIdx).getReg();
+
+          const MachineOperand &DstMO = mi->getOperand(DstIdx);
+          unsigned regA = DstMO.getReg();
+          IsEarlyClobber |= DstMO.isEarlyClobber();
+
           // Grab regB from the instruction because it may have changed if the
           // instruction was commuted.
           regB = mi->getOperand(SrcIdx).getReg();
@@ -1196,15 +1201,17 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
         }
 
         if (AllUsesCopied) {
-          // Replace other (un-tied) uses of regB with LastCopiedReg.
-          for (unsigned i = 0, e = mi->getNumOperands(); i != e; ++i) {
-            MachineOperand &MO = mi->getOperand(i);
-            if (MO.isReg() && MO.getReg() == regB && MO.isUse()) {
-              if (MO.isKill()) {
-                MO.setIsKill(false);
-                RemovedKillFlag = true;
+          if (!IsEarlyClobber) {
+            // Replace other (un-tied) uses of regB with LastCopiedReg.
+            for (unsigned i = 0, e = mi->getNumOperands(); i != e; ++i) {
+              MachineOperand &MO = mi->getOperand(i);
+              if (MO.isReg() && MO.getReg() == regB && MO.isUse()) {
+                if (MO.isKill()) {
+                  MO.setIsKill(false);
+                  RemovedKillFlag = true;
+                }
+                MO.setReg(LastCopiedReg);
               }
-              MO.setReg(LastCopiedReg);
             }
           }
 

diff --git a/test/CodeGen/Thumb2/2011-06-07-TwoAddrEarlyClobber.ll b/test/CodeGen/Thumb2/2011-06-07-TwoAddrEarlyClobber.ll
new file mode 100644 (file)
index 0000000..9e6d78e
--- /dev/null
+++ b/test/CodeGen/Thumb2/2011-06-07-TwoAddrEarlyClobber.ll
@@ -0,0 +1,36 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:32-f32:32:32-f64:32:32-v64:32:64-v128:32:128-a0:0:32-n32"
+target triple = "thumbv7-apple-darwin10"
+
+%struct.op = type { %struct.op*, %struct.op*, %struct.op* ()*, i32, i16, i16, i8, i8 }
+
+; CHECK: Perl_ck_sort
+; CHECK: ldr
+; CHECK: mov [[REGISTER:(r[0-9]+)|(lr)]]
+; CHECK: str {{(r[0-9])|(lr)}}, {{\[}}[[REGISTER]]{{\]}}, #24
+
+define void @Perl_ck_sort() nounwind optsize {
+entry:
+  %tmp27 = load %struct.op** undef, align 4
+  switch i16 undef, label %if.end151 [
+    i16 178, label %if.then60
+    i16 177, label %if.then60
+  ]
+
+if.then60:                                        ; preds = %if.then40
+  br i1 undef, label %if.then67, label %if.end95
+
+if.then67:                                        ; preds = %if.then60
+  %op_next71 = getelementptr inbounds %struct.op* %tmp27, i32 0, i32 0
+  store %struct.op* %tmp27, %struct.op** %op_next71, align 4
+  %0 = getelementptr inbounds %struct.op* %tmp27, i32 1, i32 0
+  br label %if.end95
+
+if.end95:                                         ; preds = %if.else92, %if.then67
+  %.pre-phi = phi %struct.op** [ undef, %if.then60 ], [ %0, %if.then67 ]
+  %tmp98 = load %struct.op** %.pre-phi, align 4
+  br label %if.end151
+
+if.end151:                                        ; preds = %if.end100, %if.end, %entry
+  ret void
+}