[llvm] r231299 - DWARFFormValue: Add getAsSignedConstant method.

Frédéric Riss friss at apple.com
Thu Mar 5 06:46:41 PST 2015


> On Mar 5, 2015, at 6:17 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
> 
> On Wed, Mar 4, 2015 at 5:07 PM, Frederic Riss <friss at apple.com <mailto:friss at apple.com>> wrote:
>> Author: friss
>> Date: Wed Mar  4 16:07:41 2015
>> New Revision: 231299
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=231299&view=rev
>> Log:
>> DWARFFormValue: Add getAsSignedConstant method.
>> 
>> The implementation accepts explicitely signed forms (DW_FORM_sdata),
>> but also unsigned forms as long as they fit in an int64_t.
>> 
>> Modified:
>>    llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFFormValue.h
>>    llvm/trunk/lib/DebugInfo/DWARF/DWARFFormValue.cpp
>>    llvm/trunk/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
>> 
>> Modified: llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFFormValue.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFFormValue.h?rev=231299&r1=231298&r2=231299&view=diff
>> ==============================================================================
>> --- llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFFormValue.h (original)
>> +++ llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFFormValue.h Wed Mar  4 16:07:41 2015
>> @@ -74,6 +74,7 @@ public:
>>   /// DWARFFormValue has form class is suitable for representing Foo.
>>   Optional<uint64_t> getAsReference(const DWARFUnit *U) const;
>>   Optional<uint64_t> getAsUnsignedConstant() const;
>> +  Optional<int64_t> getAsSignedConstant() const;
>>   Optional<const char *> getAsCString(const DWARFUnit *U) const;
>>   Optional<uint64_t> getAsAddress(const DWARFUnit *U) const;
>>   Optional<uint64_t> getAsSectionOffset() const;
>> 
>> Modified: llvm/trunk/lib/DebugInfo/DWARF/DWARFFormValue.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARF/DWARFFormValue.cpp?rev=231299&r1=231298&r2=231299&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/DebugInfo/DWARF/DWARFFormValue.cpp (original)
>> +++ llvm/trunk/lib/DebugInfo/DWARF/DWARFFormValue.cpp Wed Mar  4 16:07:41 2015
>> @@ -18,6 +18,7 @@
>> #include "llvm/Support/Format.h"
>> #include "llvm/Support/raw_ostream.h"
>> #include <cassert>
>> +#include <climits>
>> using namespace llvm;
>> using namespace dwarf;
>> using namespace syntax;
>> @@ -557,6 +558,24 @@ Optional<uint64_t> DWARFFormValue::getAs
>>   return Value.uval;
>> }
>> 
>> +Optional<int64_t> DWARFFormValue::getAsSignedConstant() const {
>> +  if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag)) ||
>> +      (Form == DW_FORM_udata && uint64_t(LLONG_MAX) < Value.uval))
>> +    return None;
>> +  switch (Form) {
>> +  case DW_FORM_data4:
>> +    return int32_t(Value.uval);
>> +  case DW_FORM_data2:
>> +    return int16_t(Value.uval);
>> +  case DW_FORM_data1:
>> +    return int8_t(Value.uval);
>> +  case DW_FORM_sdata:
>> +  case DW_FORM_data8:
>> +  default:
>> +    return Value.sval;
>> +  }
>> +}
>> +
>> Optional<ArrayRef<uint8_t>> DWARFFormValue::getAsBlock() const {
>>   if (!isFormClass(FC_Block) && !isFormClass(FC_Exprloc))
>>     return None;
>> 
>> Modified: llvm/trunk/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp?rev=231299&r1=231298&r2=231299&view=diff
>> ==============================================================================
>> --- llvm/trunk/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp (original)
>> +++ llvm/trunk/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp Wed Mar  4 16:07:41 2015
>> @@ -8,7 +8,10 @@
>> //===----------------------------------------------------------------------===//
>> 
>> #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
>> +#include "llvm/ADT/SmallString.h"
>> #include "llvm/Support/Dwarf.h"
>> +#include "llvm/Support/LEB128.h"
>> +#include "llvm/Support/Host.h"
>> #include "gtest/gtest.h"
>> using namespace llvm;
>> using namespace dwarf;
>> @@ -46,4 +49,75 @@ TEST(DWARFFormValue, FormClass) {
>>   EXPECT_TRUE(isFormClass(DW_FORM_ref_sig8, DWARFFormValue::FC_Reference));
>> }
>> 
>> +template<typename RawTypeT>
>> +DWARFFormValue createDataXFormValue(uint16_t Form, RawTypeT Value) {
>> +  char Raw[sizeof(RawTypeT)];
>> +  memcpy(Raw, &Value, sizeof(RawTypeT));
>> +  uint32_t Offset = 0;
>> +  DWARFFormValue Result(Form);
>> +  DataExtractor Data(StringRef(Raw, sizeof(RawTypeT)),
>> +                     sys::IsLittleEndianHost, sizeof(void*));
>> +  Result.extractValue(Data, &Offset, nullptr);
>> +  return Result;
>> +}
>> +
>> +DWARFFormValue createULEBFormValue(uint64_t Value) {
>> +  SmallString<10> RawData;
>> +  raw_svector_ostream OS(RawData);
>> +  encodeULEB128(Value, OS);
>> +  uint32_t Offset = 0;
>> +  DWARFFormValue Result(DW_FORM_udata);
>> +  DataExtractor Data(OS.str(), sys::IsLittleEndianHost, sizeof(void*));
>> +  Result.extractValue(Data, &Offset, nullptr);
>> +  return Result;
>> +}
>> +
>> +DWARFFormValue createSLEBFormValue(int64_t Value) {
>> +  SmallString<10> RawData;
>> +  raw_svector_ostream OS(RawData);
>> +  encodeSLEB128(Value, OS);
>> +  uint32_t Offset = 0;
>> +  DWARFFormValue Result(DW_FORM_sdata);
>> +  DataExtractor Data(OS.str(), sys::IsLittleEndianHost, sizeof(void*));
>> +  Result.extractValue(Data, &Offset, nullptr);
>> +  return Result;
>> +}
>> +
>> +TEST(DWARFFormValue, SignedConstantForms) {
>> +  // Check that we correctly sign extend fixed size forms.
>> +  auto Sign1 = createDataXFormValue<uint8_t>(DW_FORM_data1, -123);
>> +  auto Sign2 = createDataXFormValue<uint16_t>(DW_FORM_data2, -12345);
>> +  auto Sign4 = createDataXFormValue<uint32_t>(DW_FORM_data4, -123456789);
>> +  auto Sign8 = createDataXFormValue<uint64_t>(DW_FORM_data8, -1);
>> +  EXPECT_EQ(Sign1.getAsSignedConstant().getValue(), -123);
>> +  EXPECT_EQ(Sign2.getAsSignedConstant().getValue(), -12345);
>> +  EXPECT_EQ(Sign4.getAsSignedConstant().getValue(), -123456789);
>> +  EXPECT_EQ(Sign8.getAsSignedConstant().getValue(), -1);
>> +
>> +  // Check that we can handle big positive values, but that we return
>> +  // an error just over the limit.
>> +  auto UMax = createULEBFormValue(LLONG_MAX);
>> +  auto TooBig = createULEBFormValue(LLONG_MAX + 1);
> 
> This test is now triggering:
> 
> DWARFFormValueTest.cpp: In member function ‘virtual void
> {anonymous}::DWARFFormValue_SignedConstantForms_Test::TestBody()’:
> DWARFFormValueTest.cpp:100:49: warning: integer overflow in expression
> [-Woverflow]
> 
> We can silence this with casts, but I'm not certain if that alters
> your test case to no longer test what you require.

Thanks for the heads up. Should be fixed by r231368.
How come I didn’t see this, isn’t -Woverflow enabled by default?

Fred

> ~Aaron
> 
>> +  EXPECT_EQ(UMax.getAsSignedConstant().getValue(), LLONG_MAX);
>> +  EXPECT_EQ(TooBig.getAsSignedConstant().hasValue(), false);
>> +
>> +  // Sanity check some other forms.
>> +  auto Data1 = createDataXFormValue<uint8_t>(DW_FORM_data1, 120);
>> +  auto Data2 = createDataXFormValue<uint16_t>(DW_FORM_data2, 32000);
>> +  auto Data4 = createDataXFormValue<uint32_t>(DW_FORM_data4, 2000000000);
>> +  auto Data8 = createDataXFormValue<uint64_t>(DW_FORM_data8, 0x1234567812345678LL);
>> +  auto LEBMin = createSLEBFormValue(LLONG_MIN);
>> +  auto LEBMax = createSLEBFormValue(LLONG_MAX);
>> +  auto LEB1 = createSLEBFormValue(-42);
>> +  auto LEB2 = createSLEBFormValue(42);
>> +  EXPECT_EQ(Data1.getAsSignedConstant().getValue(), 120);
>> +  EXPECT_EQ(Data2.getAsSignedConstant().getValue(), 32000);
>> +  EXPECT_EQ(Data4.getAsSignedConstant().getValue(), 2000000000);
>> +  EXPECT_EQ(Data8.getAsSignedConstant().getValue(), 0x1234567812345678LL);
>> +  EXPECT_EQ(LEBMin.getAsSignedConstant().getValue(), LLONG_MIN);
>> +  EXPECT_EQ(LEBMax.getAsSignedConstant().getValue(), LLONG_MAX);
>> +  EXPECT_EQ(LEB1.getAsSignedConstant().getValue(), -42);
>> +  EXPECT_EQ(LEB2.getAsSignedConstant().getValue(), 42);
>> +}
>> +
>> } // end anonymous namespace
>> 
>> 
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