[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
Chris Lattner
lattner at cs.uiuc.edu
Sat Feb 4 23:54:15 PST 2006
Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.417 -> 1.418
---
Log message:
Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) [urem only].
Turn A / (C1 << N), where C1 is "1<<C2" into A >> (N+C2) [udiv only].
Tested with: rem.ll:test5, div.ll:test10
---
Diffs of the changes: (+35 -0)
InstructionCombining.cpp | 35 +++++++++++++++++++++++++++++++++++
1 files changed, 35 insertions(+)
Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.417 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.418
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.417 Sun Jan 22 17:32:06 2006
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Sun Feb 5 01:54:04 2006
@@ -1261,6 +1261,25 @@
InsertNewInstBefore(Div, I);
return new CastInst(Div, I.getType());
}
+ } else {
+ // Known to be an unsigned division.
+ if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
+ // Turn A / (C1 << N), where C1 is "1<<C2" into A >> (N+C2) [udiv only].
+ if (RHSI->getOpcode() == Instruction::Shl &&
+ isa<ConstantUInt>(RHSI->getOperand(0))) {
+ unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
+ if (isPowerOf2_64(C1)) {
+ unsigned C2 = Log2_64(C1);
+ Value *Add = RHSI->getOperand(1);
+ if (C2) {
+ Constant *C2V = ConstantUInt::get(Add->getType(), C2);
+ Add = InsertNewInstBefore(BinaryOperator::createAdd(Add, C2V,
+ "tmp"), I);
+ }
+ return new ShiftInst(Instruction::Shr, Op0, Add);
+ }
+ }
+ }
}
return 0;
@@ -1352,6 +1371,22 @@
if (LHS->equalsInt(0))
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
+ // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) [urem only].
+ if (I.getType()->isUnsigned() &&
+ RHSI->getOpcode() == Instruction::Shl &&
+ isa<ConstantUInt>(RHSI->getOperand(0))) {
+ unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
+ if (isPowerOf2_64(C1)) {
+ Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
+ Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
+ "tmp"), I);
+ return BinaryOperator::createAnd(Op0, Add);
+ }
+ }
+ }
+
return 0;
}
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