From 799ffeede17c6fb0b00ad9cc33901fe90b12e21c Mon Sep 17 00:00:00 2001
From: "Vikram S. Adve" <vadve@cs.uiuc.edu>
Date: Wed, 2 Jul 2003 01:23:15 +0000
Subject: [PATCH] (1) Major bug fix: DecomposeArrayRef() replaces its argument
 instr. and     deletes it, but we were merrily trying to fix the operands of
 that     instruction anyway!  Instead, fix the replacement instruction.

(2) An Improvement: Check for and extract global values in all operands,
    not just in known pointer operands.  For example, they can occur in
    call arguments, and probably other unforeseeable places as well.
    This also eliminates the special-case handling of Load and Store.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7053 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/SparcV9/SparcV9PreSelection.cpp | 67 +++++++---------------
 1 file changed, 22 insertions(+), 45 deletions(-)

diff --git a/lib/Target/SparcV9/SparcV9PreSelection.cpp b/lib/Target/SparcV9/SparcV9PreSelection.cpp
index 1d8bb80bb87..13f5f6e8543 100644
--- a/lib/Target/SparcV9/SparcV9PreSelection.cpp
+++ b/lib/Target/SparcV9/SparcV9PreSelection.cpp
@@ -144,10 +144,8 @@ namespace {
     // These methods do the actual work of specializing code
     void visitInstruction(Instruction &I);   // common work for every instr. 
     void visitGetElementPtrInst(GetElementPtrInst &I);
-    void visitLoadInst(LoadInst &I);
     void visitCastInst(CastInst &I);
     void visitCallInst(CallInst &I);
-    void visitStoreInst(StoreInst &I);
 
     // Helper functions for visiting operands of every instruction
     // 
@@ -243,9 +241,11 @@ inline void
 PreSelection::visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
                               Instruction& insertBefore)
 {
+  assert(&insertBefore != NULL && "Must have instruction to insert before.");
+
   if (GetElementPtrInst* gep = getGlobalAddr(Op, insertBefore)) {
     I.setOperand(opNum, gep);           // replace global operand
-    return;
+    return;                             // nothing more to do for this op.
   }
 
   Constant* CV  = dyn_cast<Constant>(Op);
@@ -322,52 +322,33 @@ PreSelection::visitInstruction(Instruction &I)
 void
 PreSelection::visitGetElementPtrInst(GetElementPtrInst &I)
 { 
-  // Check for a global and put its address into a register before this instr
-  if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), I))
-    I.setOperand(I.getPointerOperandIndex(), gep); // replace pointer operand
+  Instruction* curI = &I;
 
   // Decompose multidimensional array references
-  DecomposeArrayRef(&I);
+  if (I.getNumIndices() >= 2) {
+    // DecomposeArrayRef() replaces I and deletes it, if successful,
+    // so remember predecessor in order to find the replacement instruction.
+    // Also remember the basic block in case there is no predecessor.
+    Instruction* prevI = I.getPrev();
+    BasicBlock* bb = I.getParent();
+    if (DecomposeArrayRef(&I))
+      // first instr. replacing I
+      curI = cast<GetElementPtrInst>(prevI? prevI->getNext() : &bb->front());
+  }
 
   // Perform other transformations common to all instructions
-  visitInstruction(I);
-}
-
-
-// Load instructions: check if pointer is a global
-void
-PreSelection::visitLoadInst(LoadInst &I)
-{ 
-  // Check for a global and put its address into a register before this instr
-  if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), I))
-    I.setOperand(I.getPointerOperandIndex(), gep); // replace pointer operand
-
-  // Perform other transformations common to all instructions
-  visitInstruction(I);
-}
-
-
-// Store instructions: check if pointer is a global
-void
-PreSelection::visitStoreInst(StoreInst &I)
-{ 
-  // Check for a global and put its address into a register before this instr
-  if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), I))
-    I.setOperand(I.getPointerOperandIndex(), gep); // replace pointer operand
-
-  // Perform other transformations common to all instructions
-  visitInstruction(I);
+  visitInstruction(*curI);
 }
 
 
 // Cast instructions:
-// -- check if argument is a global
 // -- make multi-step casts explicit:
 //    -- float/double to uint32_t:
 //         If target does not have a float-to-unsigned instruction, we
 //         need to convert to uint64_t and then to uint32_t, or we may
 //         overflow the signed int representation for legal uint32_t
 //         values.  Expand this without checking target.
+// -- other common transformations on operands
 // 
 void
 PreSelection::visitCastInst(CastInst &I)
@@ -375,16 +356,12 @@ PreSelection::visitCastInst(CastInst &I)
   CastInst* castI = NULL;
 
   // Check for a global and put its address into a register before this instr
-  if (GetElementPtrInst* gep = getGlobalAddr(I.getOperand(0), I))
-    {
-      I.setOperand(0, gep);             // replace pointer operand
-    }
-  else if (I.getType() == Type::UIntTy &&
-           I.getOperand(0)->getType()->isFloatingPoint())
-    { // insert a cast-fp-to-long before I, and then replace the operand of I
-      castI = new CastInst(I.getOperand(0), Type::LongTy, "fp2Long2Uint", &I);
-      I.setOperand(0, castI);           // replace fp operand with long
-    }
+  if (I.getType() == Type::UIntTy &&
+      I.getOperand(0)->getType()->isFloatingPoint()) {
+    // insert a cast-fp-to-long before I, and then replace the operand of I
+    castI = new CastInst(I.getOperand(0), Type::LongTy, "fp2Long2Uint", &I);
+    I.setOperand(0, castI);           // replace fp operand with long
+  }
 
   // Perform other transformations common to all instructions
   visitInstruction(I);