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Fix issue #2: use zero extend to convert bool->int, not sign extend.

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This way, we match C/C++ in that casting a bool to an int gives either the value
zero or the value one.  There is a new stdlib function int sign_extend(bool)
that does sign extension for cases where that's desired.
This commit is contained in:
Matt Pharr
2011-07-12 13:30:05 +01:00
parent 6e8af5038b
commit a535aa586b
8 changed files with 94 additions and 28 deletions
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17
expr.cpp
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@@ -3673,14 +3673,7 @@ lTypeConvAtomic(FunctionEmitContext *ctx, llvm::Value *exprVal,
if (fromType->IsVaryingType() &&
LLVMTypes::BoolVectorType == LLVMTypes::Int32VectorType)
exprVal = ctx->TruncInst(exprVal, LLVMTypes::Int1VectorType, "bool_to_i1");
// FIXME: we're currently doing sign extension rather than zero
// extension here, which means that ints will have the value
// 0xffffffff for 'true' bools (versus the value 1). There is
// some code in stdlib.ispc that depends on bool->int conversions
// having this behavior that needs to be cleaned up (e.g. to
// call a __sext() builtin to do bool->int conversions) if we
// are going to fix this here.
cast = ctx->SExtInst(exprVal, targetType, "bool2int");
cast = ctx->ZExtInst(exprVal, targetType, "bool2int");
break;
case AtomicType::TYPE_INT32:
case AtomicType::TYPE_UINT32:
@@ -3712,9 +3705,7 @@ lTypeConvAtomic(FunctionEmitContext *ctx, llvm::Value *exprVal,
if (fromType->IsVaryingType() &&
LLVMTypes::BoolVectorType == LLVMTypes::Int32VectorType)
exprVal = ctx->TruncInst(exprVal, LLVMTypes::Int1VectorType, "bool_to_i1");
// FIXME: See comments above w.r.t. fixing this to be a
// ZExtInst rather than an SExtInst...
cast = ctx->SExtInst(exprVal, targetType, "bool2uint");
cast = ctx->ZExtInst(exprVal, targetType, "bool2uint");
break;
case AtomicType::TYPE_INT32:
case AtomicType::TYPE_UINT32:
@@ -3752,7 +3743,7 @@ lTypeConvAtomic(FunctionEmitContext *ctx, llvm::Value *exprVal,
if (fromType->IsVaryingType() &&
LLVMTypes::BoolVectorType == LLVMTypes::Int32VectorType)
exprVal = ctx->TruncInst(exprVal, LLVMTypes::Int1VectorType, "bool_to_i1");
cast = ctx->SExtInst(exprVal, targetType, "bool2int64");
cast = ctx->ZExtInst(exprVal, targetType, "bool2int64");
break;
case AtomicType::TYPE_INT32:
cast = ctx->SExtInst(exprVal, targetType, "int32_to_int64");
@@ -3786,7 +3777,7 @@ lTypeConvAtomic(FunctionEmitContext *ctx, llvm::Value *exprVal,
if (fromType->IsVaryingType() &&
LLVMTypes::BoolVectorType == LLVMTypes::Int32VectorType)
exprVal = ctx->TruncInst(exprVal, LLVMTypes::Int1VectorType, "bool_to_i1");
cast = ctx->SExtInst(exprVal, targetType, "bool2uint");
cast = ctx->ZExtInst(exprVal, targetType, "bool2uint");
break;
case AtomicType::TYPE_INT32:
cast = ctx->SExtInst(exprVal, targetType, "int32_to_uint64");