[llvm-commits] CVS: llvm/lib/Target/X86/InstSelectSimple.cpp

[Chris Lattner]

Changes in directory llvm/lib/Target/X86:

InstSelectSimple.cpp updated: 1.130 -> 1.131

---
Log message:

Fix bug: Jello/2003-10-18-PHINode-ConstantExpr-CondCode-Failure.llx
This also fixes miscompilation of 176.gcc.



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Diffs of the changes:  (+21 -9)

Index: llvm/lib/Target/X86/InstSelectSimple.cpp
diff -u llvm/lib/Target/X86/InstSelectSimple.cpp:1.130 llvm/lib/Target/X86/InstSelectSimple.cpp:1.131
--- llvm/lib/Target/X86/InstSelectSimple.cpp:1.130	Sat Oct 18 00:56:40 2003
+++ llvm/lib/Target/X86/InstSelectSimple.cpp	Sat Oct 18 19:26:11 2003
@@ -490,7 +490,7 @@
     // Loop over all of the PHI nodes in the LLVM basic block...
     unsigned NumPHIs = 0;
     for (BasicBlock::const_iterator I = BB->begin();
-         PHINode *PN = (PHINode*)dyn_cast<PHINode>(I); ++I) {
+         PHINode *PN = const_cast<PHINode*>(dyn_cast<PHINode>(I)); ++I) {
 
       // Create a new machine instr PHI node, and insert it.
       unsigned PHIReg = getReg(*PN);
@@ -521,15 +521,27 @@
           ValReg = EntryIt->second;
 
         } else {        
-          // Get the incoming value into a virtual register.  If it is not
-          // already available in a virtual register, insert the computation
-          // code into PredMBB
+          // Get the incoming value into a virtual register.
           //
-          MachineBasicBlock::iterator PI = PredMBB->end();
-          while (PI != PredMBB->begin() &&
-                 TII.isTerminatorInstr((*(PI-1))->getOpcode()))
-            --PI;
-          ValReg = getReg(PN->getIncomingValue(i), PredMBB, PI);
+          Value *Val = PN->getIncomingValue(i);
+
+          // If this is a constant or GlobalValue, we may have to insert code
+          // into the basic block to compute it into a virtual register.
+          if (isa<Constant>(Val) || isa<GlobalValue>(Val)) {
+            // Because we don't want to clobber any values which might be in
+            // physical registers with the computation of this constant (which
+            // might be arbitrarily complex if it is a constant expression),
+            // just insert the computation at the top of the basic block.
+            MachineBasicBlock::iterator PI = PredMBB->begin();
+
+            // Skip over any PHI nodes though!
+            while (PI != PredMBB->end() && (*PI)->getOpcode() == X86::PHI)
+              ++PI;
+
+            ValReg = getReg(Val, PredMBB, PI);
+          } else {
+            ValReg = getReg(Val);
+          }
 
           // Remember that we inserted a value for this PHI for this predecessor
           PHIValues.insert(EntryIt, std::make_pair(PredMBB, ValReg));