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Switch to unordered floating point compares.

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In particular, this gives us desired behavior for NaNs (all compares
involving a NaN evaluate to true).  This in turn allows writing the
canonical isnan() function as "v != v".

Added isnan() to the standard library as well.
This commit is contained in:
Matt Pharr
2012-06-20 13:24:09 -07:00
parent 3bc66136b2
commit 46716aada3
6 changed files with 40 additions and 9 deletions
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12
expr.cpp
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@@ -1569,31 +1569,31 @@ lEmitBinaryCmp(BinaryExpr::Op op, llvm::Value *e0Val, llvm::Value *e1Val,
switch (op) {
case BinaryExpr::Lt:
opName = "less";
pred = isFloatOp ? llvm::CmpInst::FCMP_OLT :
pred = isFloatOp ? llvm::CmpInst::FCMP_ULT :
(isUnsignedOp ? llvm::CmpInst::ICMP_ULT : llvm::CmpInst::ICMP_SLT);
break;
case BinaryExpr::Gt:
opName = "greater";
pred = isFloatOp ? llvm::CmpInst::FCMP_OGT :
pred = isFloatOp ? llvm::CmpInst::FCMP_UGT :
(isUnsignedOp ? llvm::CmpInst::ICMP_UGT : llvm::CmpInst::ICMP_SGT);
break;
case BinaryExpr::Le:
opName = "lessequal";
pred = isFloatOp ? llvm::CmpInst::FCMP_OLE :
pred = isFloatOp ? llvm::CmpInst::FCMP_ULE :
(isUnsignedOp ? llvm::CmpInst::ICMP_ULE : llvm::CmpInst::ICMP_SLE);
break;
case BinaryExpr::Ge:
opName = "greaterequal";
pred = isFloatOp ? llvm::CmpInst::FCMP_OGE :
pred = isFloatOp ? llvm::CmpInst::FCMP_UGE :
(isUnsignedOp ? llvm::CmpInst::ICMP_UGE : llvm::CmpInst::ICMP_SGE);
break;
case BinaryExpr::Equal:
opName = "equal";
pred = isFloatOp ? llvm::CmpInst::FCMP_OEQ : llvm::CmpInst::ICMP_EQ;
pred = isFloatOp ? llvm::CmpInst::FCMP_UEQ : llvm::CmpInst::ICMP_EQ;
break;
case BinaryExpr::NotEqual:
opName = "notequal";
pred = isFloatOp ? llvm::CmpInst::FCMP_ONE : llvm::CmpInst::ICMP_NE;
pred = isFloatOp ? llvm::CmpInst::FCMP_UNE : llvm::CmpInst::ICMP_NE;
break;
default:
FATAL("error in lEmitBinaryCmp()");