[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

[Chris Lattner]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

SelectionDAGISel.cpp updated: 1.311 -> 1.312
---
Log message:

Compile CodeGen/PowerPC/fp-branch.ll to:

_intcoord_cond_next55:
LBB1_3: ;cond_next55
        lis r2, ha16(LCPI1_0)
        lfs f0, lo16(LCPI1_0)(r2)
        fcmpu cr0, f1, f0
        blt cr0, LBB1_2 ;cond_next62.exitStub
LBB1_1: ;bb72.exitStub
        li r3, 1
        blr
LBB1_2: ;cond_next62.exitStub
        li r3, 0
        blr

instead of:

_intcoord_cond_next55:
LBB1_3: ;cond_next55
        lis r2, ha16(LCPI1_0)
        lfs f0, lo16(LCPI1_0)(r2)
        fcmpu cr0, f1, f0
        bge cr0, LBB1_1 ;bb72.exitStub
LBB1_4: ;cond_next55
        lis r2, ha16(LCPI1_0)
        lfs f0, lo16(LCPI1_0)(r2)
        fcmpu cr0, f1, f0
        bnu cr0, LBB1_2 ;cond_next62.exitStub
LBB1_1: ;bb72.exitStub
        li r3, 1
        blr
LBB1_2: ;cond_next62.exitStub
        li r3, 0
        blr




---
Diffs of the changes:  (+19 -6)

 SelectionDAGISel.cpp |   25 +++++++++++++++++++------
 1 files changed, 19 insertions(+), 6 deletions(-)


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.311 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.312
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.311	Tue Oct 31 16:37:42 2006
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp	Tue Oct 31 17:06:00 2006
@@ -975,6 +975,15 @@
 ShouldEmitAsBranches(const std::vector<SelectionDAGISel::CaseBlock> &Cases) {
   if (Cases.size() != 2) return true;
   
+  // If this is two comparisons of the same values or'd or and'd together, they
+  // will get folded into a single comparison, so don't emit two blocks.
+  if ((Cases[0].CmpLHS == Cases[1].CmpLHS &&
+       Cases[0].CmpRHS == Cases[1].CmpRHS) ||
+      (Cases[0].CmpRHS == Cases[1].CmpLHS &&
+       Cases[0].CmpLHS == Cases[1].CmpRHS)) {
+    return false;
+  }
+  
   return true;
 }
 
@@ -1025,14 +1034,13 @@
         (BOp->getOpcode() == Instruction::And ||
          BOp->getOpcode() == Instruction::Or)) {
       FindMergedConditions(BOp, Succ0MBB, Succ1MBB, CurMBB, BOp->getOpcode());
-
+      // If the compares in later blocks need to use values not currently
+      // exported from this block, export them now.  This block should always
+      // be the first entry.
+      assert(SwitchCases[0].ThisBB == CurMBB && "Unexpected lowering!");
+      
       // Allow some cases to be rejected.
       if (ShouldEmitAsBranches(SwitchCases)) {
-        // If the compares in later blocks need to use values not currently
-        // exported from this block, export them now.  This block should always
-        // be the first entry.
-        assert(SwitchCases[0].ThisBB == CurMBB && "Unexpected lowering!");
-        
         for (unsigned i = 1, e = SwitchCases.size(); i != e; ++i) {
           ExportFromCurrentBlock(SwitchCases[i].CmpLHS);
           ExportFromCurrentBlock(SwitchCases[i].CmpRHS);
@@ -1044,6 +1052,11 @@
         return;
       }
       
+      // Okay, we decided not to do this, remove any inserted MBB's and clear
+      // SwitchCases.
+      for (unsigned i = 1, e = SwitchCases.size(); i != e; ++i)
+        CurMBB->getParent()->getBasicBlockList().erase(SwitchCases[i].ThisBB);
+      
       SwitchCases.clear();
     }
   }