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| -rw-r--r-- | llvm/docs/LangRef.rst | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index 8bb834b45ed..d1eaee16a66 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -366,7 +366,9 @@ added in the future: calling convention on how arguments and return values are passed, but it uses a different set of caller/callee-saved registers. This alleviates the burden of saving and recovering a large register set before and after the - call in the caller. + call in the caller. If the arguments are passed in callee-saved registers, + then they will be preserved by the callee across the call. This doesn't + apply for values returned in callee-saved registers. - On X86-64 the callee preserves all general purpose registers, except for R11. R11 can be used as a scratch register. Floating-point registers @@ -397,7 +399,10 @@ added in the future: convention also behaves identical to the `C` calling convention on how arguments and return values are passed, but it uses a different set of caller/callee-saved registers. This removes the burden of saving and - recovering a large register set before and after the call in the caller. + recovering a large register set before and after the call in the caller. If + the arguments are passed in callee-saved registers, then they will be + preserved by the callee across the call. This doesn't apply for values + returned in callee-saved registers. - On X86-64 the callee preserves all general purpose registers, except for R11. R11 can be used as a scratch register. Furthermore it also preserves |
