This reverts commit a7b78cac9a77e3ef6bbbd8ab1a559891dc693401. With updates to the tests. TestWatchTaggedAddress.py: Updated the expected watchpoint types, though I'm not sure there should be a differnt default for the two ways of setting them, that needs to be confirmed. TestStepOverWatchpoint.py: Skipped this everywhere because I think what used to happen is you couldn't put 2 watchpoints on the same address (after alignment). I guess that this is now allowed because modify watchpoints aren't accounted for, but likely should be. Needs investigating.
This reverts commit 933ad5c897ee366759a54869b35b2d7285a92137. This caused 1 test failure and an unexpected pass on AArch64 Linux: https://lab.llvm.org/buildbot/#/builders/96/builds/45765 Wasn't reported because the bot was already red at the time.
Watchpoints in lldb can be either 'read', 'write', or 'read/write'. This is exposing the actual behavior of hardware watchpoints. gdb has a different behavior: a "write" type watchpoint only stops when the watched memory region *changes*. A user is using a watchpoint for one of three reasons: 1. Want to find what is changing/corrupting this memory. 2. Want to find what is writing to this memory. 3. Want to find what is reading from this memory. I believe (1) is the most common use case for watchpoints, and it currently can't be done in lldb -- the user needs to continue every time the same value is written to the watched-memory manually. I think gdb's behavior is the correct one. There are some use cases where a developer wants to find every function that writes/reads to/from a memory region, regardless of value, I want to still allow that functionality. This is also a bit of groundwork for my large watchpoint support proposal https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116 where I will be adding support for AArch64 MASK watchpoints which watch power-of-2 memory regions. A user might ask to watch 24 bytes, and a MASK watchpoint stub can do this with a 32-byte MASK watchpoint if it is properly aligned. And we need to ignore writes to the final 8 bytes of that watched region, and not show those hits to the user. This patch adds a new 'modify' watchpoint type and it is the default. Re-landing this patch after addressing testsuite failures found in CI on Linux, Intel machines, and windows. rdar://108234227
TestStepOverWatchpoint.py and TestUnalignedWatchpoint.py are failing on the ubuntu and debian bots https://lab.llvm.org/buildbot/#/builders/68/builds/60204 https://lab.llvm.org/buildbot/#/builders/96/builds/45623 and the newly added test TestModifyWatchpoint.py does not work on windows bot https://lab.llvm.org/buildbot/#/builders/219/builds/5708 I will debug tomorrow morning and reland. This reverts commit 3692267ca8f9c51cb55e4387283762d921fe2ae2.
Watchpoints in lldb can be either 'read', 'write', or 'read/write'. This is exposing the actual behavior of hardware watchpoints. gdb has a different behavior: a "write" type watchpoint only stops when the watched memory region *changes*. A user is using a watchpoint for one of three reasons: 1. Want to find what is changing/corrupting this memory. 2. Want to find what is writing to this memory. 3. Want to find what is reading from this memory. I believe (1) is the most common use case for watchpoints, and it currently can't be done in lldb -- the user needs to continue every time the same value is written to the watched-memory manually. I think gdb's behavior is the correct one. There are some use cases where a developer wants to find every function that writes/reads to/from a memory region, regardless of value, I want to still allow that functionality. This is also a bit of groundwork for my large watchpoint support proposal https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116 where I will be adding support for AArch64 MASK watchpoints which watch power-of-2 memory regions. A user might ask to watch 24 bytes, and a MASK watchpoint stub can do this with a 32-byte MASK watchpoint if it is properly aligned. And we need to ignore writes to the final 8 bytes of that watched region, and not show those hits to the user. This patch adds a new 'modify' watchpoint type and it is the default. rdar://108234227