On Sat, 9 Jul 2022 07:46:39 GMT, Julian Waters <jwat...@openjdk.org> wrote:
>> Several instances of function pointers in jdk.crypto.cryptoki are marked >> with the dllimport attribute, which should only be applied to symbol >> declarations, of which a typedef'd function pointer is not. This would only >> be useful if a function pointer defined in the linked dll is desired to be >> imported, not if the pointer itself is created locally and used to store a >> function address. In addition to being incorrect, at least on the versions >> of Visual C++ the JDK supports today, it is also redundant; Typically they >> are used to avoid an indirect stub that jumps to the proper entry in the >> import address table, but usage of these typedefs involves loading the >> address of a function and directly (Usually through GetProcAddress, even in >> other cases it would simply be set to the address of a function anyway) >> assigning it to the pointer before immediately dispatching when called, >> which bypasses this procedure entirely and makes the attribute pointless. > > Julian Waters has updated the pull request with a new target base due to a > merge or a rebase. The incremental webrev excludes the unrelated changes > brought in by the merge/rebase. The pull request contains two additional > commits since the last revision: > > - Merge branch 'master' into typedefs > - Remove __declspec(dllimport) from pointers Tested with `Microsoft (R) C/C++ Optimizing Compiler Version 19.31.31104` while observing `FPTR_VersionCheck` used in the method `JNIEXPORT jboolean JNICALL Java_sun_security_pkcs11_Secmod_nssVersionCheck` (j2secmod.c, line 40 and line 54), no differences in the generated assembly snippets: Without __declspec(dllimport): 0: 48 83 ec 38 sub $0x38,%rsp 4: 48 8d 0d 00 00 00 00 lea 0x0(%rip),%rcx # b <main+0xb> b: ff 54 24 20 call *0x20(%rsp) f: 33 c0 xor %eax,%eax 11: 48 83 c4 38 add $0x38,%rsp 15: c3 ret ``` With __declspec(dllimport): 0: 48 83 ec 38 sub $0x38,%rsp 4: 48 8d 0d 00 00 00 00 lea 0x0(%rip),%rcx # b <main+0xb> b: ff 54 24 20 call *0x20(%rsp) f: 33 c0 xor %eax,%eax 11: 48 83 c4 38 add $0x38,%rsp 15: c3 ret ------------- PR: https://git.openjdk.org/jdk/pull/9353
