[Orc] Make the ObjectLinkingLayer take ownership of object files until

[oota-llvm.git] / docs / StackMaps.rst

diff --git a/docs/StackMaps.rst b/docs/StackMaps.rst
index 373596df8c88095c2122b45e3b5e59e015d47122..43c60c9e7850dbeba38a33bc313cf5adb3891f4e 100644 (file)
--- a/docs/StackMaps.rst
+++ b/docs/StackMaps.rst
@@ -221,6 +221,13 @@ lowered according to the calling convention specified at the
 intrinsic's callsite. Variants of the intrinsic with non-void return
 type also return a value according to calling convention.
 
 intrinsic's callsite. Variants of the intrinsic with non-void return
 type also return a value according to calling convention.
 

+On PowerPC, note that ``<target>`` must be the actual intended target of
+the indirect call. Specifically, even when compiling for the ELF V1 ABI,
+``<target>`` is not the function-descriptor address normally used as the C/C++
+function-pointer representation. As a result, the call target must be local
+because no adjustment or restoration of the TOC pointer (in register r2) will
+be performed.
+

 Requesting zero patch point arguments is valid. In this case, all
 variable operands are handled just like
 ``llvm.experimental.stackmap.*``. The difference is that space will
 Requesting zero patch point arguments is valid. In this case, all
 variable operands are handled just like
 ``llvm.experimental.stackmap.*``. The difference is that space will


@@ -400,6 +407,10 @@ immediately after compiling a module and encode the information in its
 own format. Since the runtime controls the allocation of sections, it
 can reuse the same stack map space for multiple modules.
 
 own format. Since the runtime controls the allocation of sections, it
 can reuse the same stack map space for multiple modules.
 

+Stackmap support is currently only implemented for 64-bit
+platforms. However, a 32-bit implementation should be able to use the
+same format with an insignificant amount of wasted space.
+

 .. _stackmap-section:
 
 Stack Map Section
 .. _stackmap-section:
 
 Stack Map Section


@@ -454,10 +465,11 @@ program could crash before the runtime could take back control.
 
 To enforce these semantics, stackmap and patchpoint intrinsics are
 considered to potentially read and write all memory. This may limit
 
 To enforce these semantics, stackmap and patchpoint intrinsics are
 considered to potentially read and write all memory. This may limit

-optimization more than some clients desire. To address this problem
-meta-data could be added to the intrinsic call to express aliasing,
-thereby allowing optimizations to hoist certain loads above stack
-maps.
+optimization more than some clients desire. This limitation may be
+avoided by marking the call site as "readonly". In the future we may
+also allow meta-data to be added to the intrinsic call to express
+aliasing, thereby allowing optimizations to hoist certain loads above
+stack maps.

 
 Direct Stack Map Entries
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
 Direct Stack Map Entries
 ^^^^^^^^^^^^^^^^^^^^^^^^