Skip to content

Nits for rdtsc and rdtscp #4899

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jan 18, 2024
Merged

Nits for rdtsc and rdtscp #4899

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions docs/intrinsics/rdtsc.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -62,4 +62,5 @@ int main()

## See also

[__rdtscp](../intrinsics/rdtscp.md)\
[Compiler intrinsics](../intrinsics/compiler-intrinsics.md)
4 changes: 2 additions & 2 deletions docs/intrinsics/rdtscp.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ ms.assetid: f17d9a9c-88bb-44e0-b69d-d516bc1c93ee

**Microsoft Specific**

Generates the `rdtscp` instruction, writes `TSC_AUX[31:0`] to memory, and returns the 64-bit Time Stamp Counter (`TSC)` result.
Generates the `rdtscp` instruction, writes `TSC_AUX[31:0]` to memory, and returns the 64-bit Time Stamp Counter (TSC) result.

## Syntax

Expand Down Expand Up @@ -39,7 +39,7 @@ A 64-bit unsigned integer tick count.

## Remarks

The `__rdtscp` intrinsic generates the `rdtscp` instruction. To determine hardware support for this instruction, call the `__cpuid` intrinsic with `InfoType=0x80000001` and check bit 27 of `CPUInfo[3] (EDX)`. This bit is 1 if the instruction is supported, and 0 otherwise. If you run code that uses the intrinsic on hardware that doesn't support the `rdtscp` instruction, the results are unpredictable.
The `__rdtscp` intrinsic generates the `rdtscp` instruction. To determine hardware support for this instruction, call the `__cpuid` intrinsic with `InfoType=0x80000001` and check bit 27 of `CPUInfo[3] (EDX)`. This bit is 1 if the instruction is supported, and 0 otherwise. If you run code that uses the intrinsic on hardware that doesn't support the `rdtscp` instruction, the results are unpredictable.

This instruction waits until all previous instructions have executed and all previous loads are globally visible. However, it isn't a serializing instruction. For more information, see the Intel and AMD manuals.

Expand Down