RFR: 8308850: Change JVM options with small ranges from 64 to 32 bits, for globals.hpp [v3]

[David Holmes]

On Mon, 7 Aug 2023 14:52:44 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Actually this counts bytecodes, so it could easily become 64 bit on 64 bit platforms.
>
> This is complicated.  BytecodeCounter::_counter_value is an int, and StopInterpreterAt compares to that in shared code, which is fine because it'll promote the former to intx.  The cpu-specific code fetches the former as int and the latter as intx, except in one place so fixing either is going to be work.  The one place that complains on x86 is 
> 
> src/hotspot/cpu/x86/templateInterpreterGenerator_x86.cpp:1865:12: warning: conversion from 'intx' {aka 'long int'} to 'int32_t' {aka 'int'} may change value [-Wconversion]
>  1865 |            StopInterpreterAt,
>       |            ^~~~~~~~~~~~~~~~~
> 
> 
>   __ cmp32(ExternalAddress((address) &BytecodeCounter::_counter_value),
>            StopInterpreterAt,
>            rscratch1);
> 
> We could just static_cast StopInterpreterAt to int here.

> Actually this counts bytecodes, so it could easily become 64 bit on 64 bit platforms.

I thought this was the count within a method, in which case the bytecode limit is the same for 32-bit and 64-bit.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15164#discussion_r1288037015