When gen jal or jalr, retain some memory before pop BlockTrampolinePool.

[luyahan]

RecordCallPosition record current pc into SafepointTable.
If pop a TrampolinePool after jalr, return address in stack cant't be found in SafepointTable.
Fix #56.
Fix #129

[penguinwu]

Great work @luyahan!

Could you give an example of the problem the is prevented by the fix?

[ghost]

LGTM. Nice discovery!

[luyahan]

Great work @luyahan!

Could you give an example of the problem the is prevented by the fix?

In code-generator-riscv64.cc:615, it call RecordCallPosition to record the pc after Call into SafepointTable. But if Call pop a BlockTrampolinePool like it :

                  [ kArchCallCodeObject
                  -- Inlined Trampoline to CEntry_Return1_DontSaveFPRegs_ArgvOnStack_NoBuiltinExit --
0x9be7ec53f0   f30  00000fb7       lui       t6, 0x0         ;; off heap target
0x9be7ec53f4   f34  7f6f8f9b       addiw     t6, t6, 2038
0x9be7ec53f8   f38  00cf9f93       slli      t6, t6, 12
0x9be7ec53fc   f3c  c9af8f93       addi      t6, t6, -870
0x9be7ec5400   f40  00cf9f93       slli      t6, t6, 12
0x9be7ec5404   f44  8a9f8f93       addi      t6, t6, -1879
0x9be7ec5408   f48  00cf9f93       slli      t6, t6, 12
0x9be7ec540c   f4c  520f8f93       addi      t6, t6, 1312
0x9be7ec5410   f50  000f80e7       jalr      t6
0x9be7ec5414   f54  0840006f       j         132 -> 0x9be7ec5498  <+0xfd8>
0x9be7ec5418   f58  7090006f       j         3848 -> 0x9be7ec6320  <+0x1e60>
0x9be7ec541c   f5c  72d0006f       j         3884 -> 0x9be7ec6348  <+0x1e88>
0x9be7ec5420   f60  7ad0006f       j         4012 -> 0x9be7ec63cc  <+0x1f0c>
0x9be7ec5424   f64  7c90006f       j         4040 -> 0x9be7ec63ec  <+0x1f2c>
0x9be7ec5428   f68  7e10006f       j         4064 -> 0x9be7ec6408  <+0x1f48>
0x9be7ec542c   f6c  7ed0006f       j         4076 -> 0x9be7ec6418  <+0x1f58>
0x9be7ec5430   f70  6900106f       j         5776 -> 0x9be7ec6ac0  <+0x2600>
0x9be7ec5434   f74  5050106f       j         7428 -> 0x9be7ec7138  <+0x2c78>
0x9be7ec5438   f78  5290106f       j         7464 -> 0x9be7ec7160  <+0x2ca0>
0x9be7ec543c   f7c  54d0106f       j         7500 -> 0x9be7ec7188  <+0x2cc8>
0x9be7ec5440   f80  5710106f       j         7536 -> 0x9be7ec71b0  <+0x2cf0>
0x9be7ec5444   f84  5950106f       j         7572 -> 0x9be7ec71d8  <+0x2d18>
0x9be7ec5448   f88  5b90106f       j         7608 -> 0x9be7ec7200  <+0x2d40>
0x9be7ec544c   f8c  5dd0106f       j         7644 -> 0x9be7ec7228  <+0x2d68>
0x9be7ec5450   f90  6010106f       j         7680 -> 0x9be7ec7250  <+0x2d90>
0x9be7ec5454   f94  6250106f       j         7716 -> 0x9be7ec7278  <+0x2db8>
0x9be7ec5458   f98  6490106f       j         7752 -> 0x9be7ec72a0  <+0x2de0>
0x9be7ec545c   f9c  66d0106f       j         7788 -> 0x9be7ec72c8  <+0x2e08>
0x9be7ec5460   fa0  6910106f       j         7824 -> 0x9be7ec72f0  <+0x2e30>
0x9be7ec5464   fa4  7050106f       j         7940 -> 0x9be7ec7368  <+0x2ea8>
0x9be7ec5468   fa8  7290106f       j         7976 -> 0x9be7ec7390  <+0x2ed0>
0x9be7ec546c   fac  74d0106f       j         8012 -> 0x9be7ec73b8  <+0x2ef8>
0x9be7ec5470   fb0  7710106f       j         8048 -> 0x9be7ec73e0  <+0x2f20>
0x9be7ec5474   fb4  7950106f       j         8084 -> 0x9be7ec7408  <+0x2f48>
0x9be7ec5478   fb8  7b90106f       j         8120 -> 0x9be7ec7430  <+0x2f70>
0x9be7ec547c   fbc  7dd0106f       j         8156 -> 0x9be7ec7458  <+0x2f98>
0x9be7ec5480   fc0  0000206f       j         8192 -> 0x9be7ec7480  <+0x2fc0>
0x9be7ec5484   fc4  0240206f       j         8228 -> 0x9be7ec74a8  <+0x2fe8>
0x9be7ec5488   fc8  0480206f       j         8264 -> 0x9be7ec74d0  <+0x3010>
0x9be7ec548c   fcc  06c0206f       j         8300 -> 0x9be7ec74f8  <+0x3038>
0x9be7ec5490   fd0  0900206f       j         8336 -> 0x9be7ec7520  <+0x3060>
0x9be7ec5494   fd4  0040006f       j         4 -> 0x9be7ec5498  <+0xfd8>
                  ]
0x9be7ec4bd8   fd8  fff00893       li        a7, -1

so record 0x9be7ec4bd8 not jalr return address 0x9be7ec5414 into safepoint tale.

This patch add a remain address after Call. It gen code like:

0x9be7ec4b34   f34  7f4f8f9b       addiw     t6, t6, 2036
0x9be7ec4b38   f38  00cf9f93       slli      t6, t6, 12
0x9be7ec4b3c   f3c  b64f8f93       addi      t6, t6, -1180
0x9be7ec4b40   f40  00cf9f93       slli      t6, t6, 12
0x9be7ec4b44   f44  b5ef8f93       addi      t6, t6, -1186
0x9be7ec4b48   f48  00cf9f93       slli      t6, t6, 12
0x9be7ec4b4c   f4c  4e0f8f93       addi      t6, t6, 1248
0x9be7ec4b50   f50  000f80e7       jalr      t6
0x9be7ec4b54   f54  fff00893       li        a7, -1
0x9be7ec4b58   f58  0840006f       j         132 -> 0x9be7ec4bdc  <+0xfdc>
0x9be7ec4b5c   f5c  7050006f       j         3844 -> 0x9be7ec5a60  <+0x1e60>
0x9be7ec4b60   f60  7290006f       j         3880 -> 0x9be7ec5a88  <+0x1e88>
0x9be7ec4b64   f64  7a90006f       j         4008 -> 0x9be7ec5b0c  <+0x1f0c>
0x9be7ec4b68   f68  7c50006f       j         4036 -> 0x9be7ec5b2c  <+0x1f2c>
0x9be7ec4b6c   f6c  7dd0006f       j         4060 -> 0x9be7ec5b48  <+0x1f48>
0x9be7ec4b70   f70  7e90006f       j         4072 -> 0x9be7ec5b58  <+0x1f58>
0x9be7ec4b74   f74  68c0106f       j         5772 -> 0x9be7ec6200  <+0x2600>
0x9be7ec4b78   f78  5010106f       j         7424 -> 0x9be7ec6878  <+0x2c78>
0x9be7ec4b7c   f7c  5250106f       j         7460 -> 0x9be7ec68a0  <+0x2ca0>
0x9be7ec4b80   f80  5490106f       j         7496 -> 0x9be7ec68c8  <+0x2cc8>
0x9be7ec4b84   f84  56d0106f       j         7532 -> 0x9be7ec68f0  <+0x2cf0>
0x9be7ec4b88   f88  5910106f       j         7568 -> 0x9be7ec6918  <+0x2d18>
0x9be7ec4b8c   f8c  5b50106f       j         7604 -> 0x9be7ec6940  <+0x2d40>
0x9be7ec4b90   f90  5d90106f       j         7640 -> 0x9be7ec6968  <+0x2d68>
0x9be7ec4b94   f94  5fd0106f       j         7676 -> 0x9be7ec6990  <+0x2d90>
0x9be7ec4b98   f98  6210106f       j         7712 -> 0x9be7ec69b8  <+0x2db8>
0x9be7ec4b9c   f9c  6450106f       j         7748 -> 0x9be7ec69e0  <+0x2de0>
0x9be7ec4ba0   fa0  6690106f       j         7784 -> 0x9be7ec6a08  <+0x2e08>
0x9be7ec4ba4   fa4  68d0106f       j         7820 -> 0x9be7ec6a30  <+0x2e30>
0x9be7ec4ba8   fa8  7010106f       j         7936 -> 0x9be7ec6aa8  <+0x2ea8>
0x9be7ec4bac   fac  7250106f       j         7972 -> 0x9be7ec6ad0  <+0x2ed0>
0x9be7ec4bb0   fb0  7490106f       j         8008 -> 0x9be7ec6af8  <+0x2ef8>
0x9be7ec4bb4   fb4  76d0106f       j         8044 -> 0x9be7ec6b20  <+0x2f20>
0x9be7ec4bb8   fb8  7910106f       j         8080 -> 0x9be7ec6b48  <+0x2f48>
0x9be7ec4bbc   fbc  7b50106f       j         8116 -> 0x9be7ec6b70  <+0x2f70>
0x9be7ec4bc0   fc0  7d90106f       j         8152 -> 0x9be7ec6b98  <+0x2f98>
0x9be7ec4bc4   fc4  7fd0106f       j         8188 -> 0x9be7ec6bc0  <+0x2fc0>
0x9be7ec4bc8   fc8  0200206f       j         8224 -> 0x9be7ec6be8  <+0x2fe8>
0x9be7ec4bcc   fcc  0440206f       j         8260 -> 0x9be7ec6c10  <+0x3010>
0x9be7ec4bd0   fd0  0680206f       j         8296 -> 0x9be7ec6c38  <+0x3038>
0x9be7ec4bd4   fd4  08c0206f       j         8332 -> 0x9be7ec6c60  <+0x3060>
0x9be7ec4bd8   fd8  0040006f       j         4 -> 0x9be7ec4bdc  <+0xfdc>
0x9be7ec4bdc   fdc  ff010113       addi      sp, sp, -16

It will reocord 0x9be7ec4b54 into safepoint table.

[ghost]

I rebased this and reopened as #144.