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print floats more accurately #1297

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print floats more accurately #1297

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15 changes: 11 additions & 4 deletions llvm_util/utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
#include "llvm_util/utils.h"
#include "ir/constant.h"
#include "ir/function.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
Expand Down Expand Up @@ -328,10 +329,16 @@ Value* get_operand(llvm::Value *v,

if (auto cnst = dyn_cast<llvm::ConstantFP>(v)) {
auto &apfloat = cnst->getValueAPF();
auto c
= make_unique<FloatConst>(*ty,
toString(apfloat.bitcastToAPInt(), 10, false),
true);
unique_ptr<FloatConst> c;
if (apfloat.isFinite()) {
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@nunoplopes nunoplopes Mar 17, 2026

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does this need to check for NaN?

llvm::SmallString<32> str;
apfloat.toString(str);
c = make_unique<FloatConst>(*ty, string(str), false);
} else {
c = make_unique<FloatConst>(*ty,
toString(apfloat.bitcastToAPInt(), 10, false),
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@nunoplopes nunoplopes Mar 17, 2026

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I'm very surprised we would need this patch. Either bitcastToAPInt is not working correctly, or something is off with the printing in constant.cpp. Representing the bit pattern of the number should be the most precise way of storing it.

true);
}
auto ret = c.get();
current_fn->addConstant(std::move(c));
RETURN_CACHE(ret);
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