diff options
Diffstat (limited to 'llvm/docs/Statepoints.rst')
| -rw-r--r-- | llvm/docs/Statepoints.rst | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/llvm/docs/Statepoints.rst b/llvm/docs/Statepoints.rst index d6576293dbd..efdbde832cd 100644 --- a/llvm/docs/Statepoints.rst +++ b/llvm/docs/Statepoints.rst @@ -142,7 +142,7 @@ resulting relocation sequence is: define i8 addrspace(1)* @test1(i8 addrspace(1)* %obj) gc "statepoint-example" { - %0 = call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @foo, i32 0, i32 0, i32 0, i8 addrspace(1)* %obj) + %0 = call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i8 addrspace(1)* %obj) %obj.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(i32 %0, i32 4, i32 4) ret i8 addrspace(1)* %obj.relocated } @@ -297,7 +297,8 @@ Syntax: :: declare i32 - @llvm.experimental.gc.statepoint(func_type <target>, + @llvm.experimental.gc.statepoint(i64 <id>, i32 <num patch bytes>, + func_type <target>, i64 <#call args>. i64 <flags>, ... (call parameters), i64 <# transition args>, ... (transition parameters), @@ -313,11 +314,31 @@ runtime. Operands: """"""""" +The 'id' operand is a constant integer that is reported as the ID +field in the generated stackmap. LLVM does not interpret this +parameter in any way and its meaning is up to the statepoint user to +decide. Note that LLVM is free to duplicate code containing +statepoint calls, and this may transform IR that had a unique 'id' per +lexical call to statepoint to IR that does not. + +If 'num patch bytes' is non-zero then the call instruction +corresponding to the statepoint is not emitted and LLVM emits 'num +patch bytes' bytes of nops in its place. LLVM will emit code to +prepare the function arguments and retrieve the function return value +in accordance to the calling convention; the former before the nop +sequence and the latter after the nop sequence. It is expected that +the user will patch over the 'num patch bytes' bytes of nops with a +calling sequence specific to their runtime before executing the +generated machine code. There are no guarantees with respect to the +alignment of the nop sequence. Unlike :doc:`StackMaps` statepoints do +not have a concept of shadow bytes. + The 'target' operand is the function actually being called. The target can be specified as either a symbolic LLVM function, or as an arbitrary Value of appropriate function type. Note that the function type must match the signature of the callee and the types of the 'call -parameters' arguments. +parameters' arguments. If 'num patch bytes' is non-zero then 'target' +has to be the constant pointer null of the appropriate function type. The '#call args' operand is the number of arguments to the actual call. It must exactly match the number of arguments passed in the @@ -506,9 +527,6 @@ Note that the Locations used in each section may describe the same physical location. e.g. A stack slot may appear as a deopt location, a gc base pointer, and a gc derived pointer. -The ID field of the 'StkMapRecord' for a statepoint is meaningless and -it's value is explicitly unspecified. - The LiveOut section of the StkMapRecord will be empty for a statepoint record. |
