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src: use struct as arguments to node::Assert #25869

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7564e4f
src: use struct as arguments to node::Assert
addaleax Feb 1, 2019
b60184f
fixup! src: use struct as arguments to node::Assert
addaleax Feb 1, 2019
9d404ba
fixup! src: use struct as arguments to node::Assert
addaleax Feb 2, 2019
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src: use struct as arguments to node::Assert 
This just makes the code a bit more obvious (subjectively).
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@addaleax
addaleax committed Feb 2, 2019
commit 7564e4fda9d51fb5580418db742e6b7f56bf0557
19 changes: 7 additions & 12 deletions src/node_errors.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -166,23 +166,18 @@ void AppendExceptionLine(Environment* env,
ABORT_NO_BACKTRACE();
}

[[noreturn]] void Assert(const char* const (*args)[4]) {
auto filename = (*args)[0];
auto linenum = (*args)[1];
auto message = (*args)[2];
auto function = (*args)[3];

[[noreturn]] void Assert(const AssertionInfo& info) {
char name[1024];
GetHumanReadableProcessName(&name);

fprintf(stderr,
"%s: %s:%s:%s%s Assertion `%s' failed.\n",
"%s: %s:%u:%s%s Assertion `%s' failed.\n",
name,
filename,
linenum,
function,
*function ? ":" : "",
message);
info.filename,
info.linenum,
info.function,
*info.function ? ":" : "",
info.message);
fflush(stderr);

Abort();
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19 changes: 13 additions & 6 deletions src/util.h
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Expand Up @@ -85,10 +85,16 @@ extern bool v8_initialized;
// whether V8 is initialized.
void LowMemoryNotification();

// The slightly odd function signature for Assert() is to ease
// instruction cache pressure in calls from CHECK.
// The reason that Assert() takes a struct argument instead of individual
// const char*s is to ease instruction cache pressure in calls from CHECK.
struct AssertionInfo {
const char* filename;
unsigned int linenum;
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const char* message;
const char* function;
};
[[noreturn]] void Assert(const AssertionInfo& info);
[[noreturn]] void Abort();
[[noreturn]] void Assert(const char* const (*args)[4]);
void DumpBacktrace(FILE* fp);

#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
Expand Down Expand Up @@ -120,9 +126,10 @@ void DumpBacktrace(FILE* fp);
#define CHECK(expr) \
do { \
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@refack refack Feb 1, 2019 •
edited
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If you're here, would you consider de-crufting this? i.e.:

    if (!(expr)) {                                                             \
      node::Assert({ __FILE__, __LINE__, #expr, PRETTY_FUNCTION_NAME });       \
    }                                                                          \

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@addaleax addaleax Feb 1, 2019

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@refack At least locally (gcc-7 on Ubuntu 18.04), that would undo the purpose of this (what the comment is referring to): It would put the object construction in-line into the code instead of ending up as a simple pointer load from the read-only data section.

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@refack refack Feb 1, 2019

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So how about:

    if (!(expr)) {                                                             \
      static constexpr args{ __FILE__, __LINE__, #expr, PRETTY_FUNCTION_NAME } \
      node::Assert(args);                                                      \
    }

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@addaleax addaleax Feb 1, 2019

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@refack You are talking about const → constexpr, right? That has the same result for me, and I don’t see it as being clearer about the intention here (having an explicit, hardcoded object in the read-only data section).

I’ll make the comment more explicit about what the idea here is.

if (UNLIKELY(!(expr))) { \
static const char* const args[] = { __FILE__, STRINGIFY(__LINE__), \
#expr, PRETTY_FUNCTION_NAME }; \
node::Assert(&args); \
static const node::AssertionInfo args = { \
__FILE__, __LINE__, #expr, PRETTY_FUNCTION_NAME \
}; \
node::Assert(args); \
} \
} while (0)

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