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Chris pointed out that it's not necessary to set i64 MUL to Expand

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on x86-32 since i64 itself is not a Legal type. And, update some
comments.

llvm-svn: 47282
This commit is contained in:
Dan Gohman 2008-02-18 19:34:53 +00:00
parent 03fd8ea753
commit 0d0f16ca85
1 changed files with 10 additions and 12 deletions
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22
lib/Target/X86/X86ISelLowering.cpp
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@ -169,13 +169,16 @@ X86TargetLowering::X86TargetLowering(TargetMachine &TM)
setOperationAction(ISD::BIT_CONVERT , MVT::i32 , Expand);
}
// Scalar integer multiply-high, divide, and remainder are
// lowered to use operations that produce two results, to match the
// available instructions. This exposes the two-result form to trivial
// CSE, which is able to combine x/y and x%y into a single instruction,
// for example. The single-result multiply instructions are introduced
// in X86ISelDAGToDAG.cpp, after CSE, for uses where the the high part
// is not needed.
// Scalar integer divide and remainder are lowered to use operations that
// produce two results, to match the available instructions. This exposes
// the two-result form to trivial CSE, which is able to combine x/y and x%y
// into a single instruction.
//
// Scalar integer multiply-high is also lowered to use two-result
// operations, to match the available instructions. However, plain multiply
// (low) operations are left as Legal, as there are single-result
// instructions for this in x86. Using the two-result multiply instructions
// when both high and low results are needed must be arranged by dagcombine.
setOperationAction(ISD::MULHS , MVT::i8 , Expand);
setOperationAction(ISD::MULHU , MVT::i8 , Expand);
setOperationAction(ISD::SDIV , MVT::i8 , Expand);
@ -201,11 +204,6 @@ X86TargetLowering::X86TargetLowering(TargetMachine &TM)
setOperationAction(ISD::SREM , MVT::i64 , Expand);
setOperationAction(ISD::UREM , MVT::i64 , Expand);
// 8, 16, and 32-bit plain multiply are legal. And 64-bit multiply
// is also legal on x86-64.
if (!Subtarget->is64Bit())
setOperationAction(ISD::MUL , MVT::i64 , Expand);
setOperationAction(ISD::BR_JT , MVT::Other, Expand);
setOperationAction(ISD::BRCOND , MVT::Other, Custom);
setOperationAction(ISD::BR_CC , MVT::Other, Expand);