X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=docs%2FLangRef.rst;h=9bcbd89c3018e84f34e144d74a91e75cf004e2e3;hb=243e7c5f8c8758318baa5954b8aa666ec1732f81;hp=ef5913b78f3858c56d63e7c7870eb9fc8135ce13;hpb=2dacece9e2c9db49f31a1e1432604f0411018290;p=oota-llvm.git diff --git a/docs/LangRef.rst b/docs/LangRef.rst index ef5913b78f3..9bcbd89c301 100644 --- a/docs/LangRef.rst +++ b/docs/LangRef.rst @@ -5138,7 +5138,7 @@ Syntax: :: - = catchpad [*] + = catchpad [*] to label unwind label Overview: @@ -5153,9 +5153,9 @@ routine requires to know if this is an appropriate place to catch the exception. Control is tranfered to the ``exception`` label if the ``catchpad`` is not an appropriate handler for the in-flight exception. The ``normal`` label should contain the code found in the ``catch`` -portion of a ``try``/``catch`` sequence. It defines values supplied by -the :ref:`personality function ` upon re-entry to the -function. The ``resultval`` has the type ``resultty``. +portion of a ``try``/``catch`` sequence. The ``resultval`` has the type +:ref:`token ` and is used to match the ``catchpad`` to +corresponding :ref:`catchrets `. Arguments: """""""""" @@ -5170,15 +5170,11 @@ label to transfer control to if it doesn't. Semantics: """""""""" -The '``catchpad``' instruction defines the values which are set by the -:ref:`personality function ` upon re-entry to the function, and -therefore the "result type" of the ``catchpad`` instruction. As with -calling conventions, how the personality function results are -represented in LLVM IR is target specific. - When the call stack is being unwound due to an exception being thrown, the exception is compared against the ``args``. If it doesn't match, then control is transfered to the ``exception`` basic block. +As with calling conventions, how the personality function results are +represented in LLVM IR is target specific. The ``catchpad`` instruction has several restrictions: @@ -5192,11 +5188,14 @@ The ``catchpad`` instruction has several restrictions: catch block. - A basic block that is not a catch block may not include a '``catchpad``' instruction. +- A catch block which has another catch block as a predecessor may not have + any other predecessors. - It is undefined behavior for control to transfer from a ``catchpad`` to a - ``cleanupret`` without first executing a ``catchret`` and a subsequent - ``cleanuppad``. -- It is undefined behavior for control to transfer from a ``catchpad`` to a - ``ret`` without first executing a ``catchret``. + ``ret`` without first executing a ``catchret`` that consumes the + ``catchpad`` or unwinding through its ``catchendpad``. +- It is undefined behavior for control to transfer from a ``catchpad`` to + itself without first executing a ``catchret`` that consumes the + ``catchpad`` or unwinding through its ``catchendpad``. Example: """""""" @@ -5204,7 +5203,7 @@ Example: .. code-block:: llvm ;; A catch block which can catch an integer. - %res = catchpad { i8*, i32 } [i8** @_ZTIi] + %tok = catchpad [i8** @_ZTIi] to label %int.handler unwind label %terminate .. _i_catchendpad: @@ -5264,7 +5263,8 @@ The ``catchendpad`` instruction has several restrictions: '``catchendpad``' instruction. - Exactly one catch block may unwind to a ``catchendpad``. - The unwind target of invokes between a ``catchpad`` and a - corresponding ``catchret`` must be its ``catchendpad``. + corresponding ``catchret`` must be its ``catchendpad`` or + an inner EH pad. Example: """""""" @@ -5284,7 +5284,7 @@ Syntax: :: - catchret label + catchret to label Overview: """"""""" @@ -5296,8 +5296,10 @@ single successor. Arguments: """""""""" -The '``catchret``' instruction requires one argument which specifies -where control will transfer to next. +The first argument to a '``catchret``' indicates which ``catchpad`` it +exits. It must be a :ref:`catchpad `. +The second argument to a '``catchret``' specifies where control will +transfer to next. Semantics: """""""""" @@ -5308,13 +5310,22 @@ whose unwinding was interrupted with a The :ref:`personality function ` gets a chance to execute arbitrary code to, for example, run a C++ destructor. Control then transfers to ``normal``. +It may be passed an optional, personality specific, value. +It is undefined behavior to execute a ``catchret`` whose ``catchpad`` has +not been executed. +It is undefined behavior to execute a ``catchret`` if any ``catchpad`` or +``cleanuppad`` has been executed, without subsequently executing a +corresponding ``catchret``/``cleanupret`` or unwinding out of the inner +pad, following the most recent execution of the ``catchret``'s corresponding +``catchpad``. + Example: """""""" .. code-block:: llvm - catchret label %continue + catchret %catch label %continue .. _i_cleanupret: @@ -5326,8 +5337,8 @@ Syntax: :: - cleanupret unwind label - cleanupret unwind to caller + cleanupret unwind label + cleanupret unwind to caller Overview: """"""""" @@ -5339,9 +5350,9 @@ an optional successor. Arguments: """""""""" -The '``cleanupret``' instruction requires one argument, which must have the -same type as the result of any '``cleanuppad``' instruction in the same -function. It also has an optional successor, ``continue``. +The '``cleanupret``' instruction requires one argument, which indicates +which ``cleanuppad`` it exits, and must be a :ref:`cleanuppad `. +It also has an optional successor, ``continue``. Semantics: """""""""" @@ -5350,14 +5361,21 @@ The '``cleanupret``' instruction indicates to the :ref:`personality function ` that one :ref:`cleanuppad ` it transferred control to has ended. It transfers control to ``continue`` or unwinds out of the function. +It is undefined behavior to execute a ``cleanupret`` whose ``cleanuppad`` has +not been executed. +It is undefined behavior to execute a ``cleanupret`` if any ``catchpad`` or +``cleanuppad`` has been executed, without subsequently executing a +corresponding ``catchret``/``cleanupret`` or unwinding out of the inner pad, +following the most recent execution of the ``cleanupret``'s corresponding +``cleanuppad``. Example: """""""" .. code-block:: llvm - cleanupret void unwind to caller - cleanupret { i8*, i32 } %exn unwind label %continue + cleanupret %cleanup unwind to caller + cleanupret %cleanup unwind label %continue .. _i_terminatepad: @@ -8390,7 +8408,7 @@ Syntax: :: - = cleanuppad [*] + = cleanuppad [*] Overview: """"""""" @@ -8402,7 +8420,8 @@ transfer control to run cleanup actions. The ``args`` correspond to whatever additional information the :ref:`personality function ` requires to execute the cleanup. -The ``resultval`` has the type ``resultty``. +The ``resultval`` has the type :ref:`token ` and is used to +match the ``cleanuppad`` to corresponding :ref:`cleanuprets `. Arguments: """""""""" @@ -8414,9 +8433,8 @@ Semantics: """""""""" The '``cleanuppad``' instruction defines the values which are set by the -:ref:`personality function ` upon re-entry to the function, and -therefore the "result type" of the ``cleanuppad`` instruction. As with -calling conventions, how the personality function results are +:ref:`personality function ` upon re-entry to the function. +As with calling conventions, how the personality function results are represented in LLVM IR is target specific. When the call stack is being unwound due to an exception being thrown, @@ -8433,18 +8451,21 @@ The ``cleanuppad`` instruction has several restrictions: cleanup block. - A basic block that is not a cleanup block may not include a '``cleanuppad``' instruction. +- All '``cleanupret``'s which exit a ``cleanuppad`` must have the same + exceptional successor. - It is undefined behavior for control to transfer from a ``cleanuppad`` to a - ``catchret`` without first executing a ``cleanupret`` and a subsequent - ``catchpad``. -- It is undefined behavior for control to transfer from a ``cleanuppad`` to a - ``ret`` without first executing a ``cleanupret``. + ``ret`` without first executing a ``cleanupret`` that consumes the + ``cleanuppad`` or unwinding out of the ``cleanuppad``. +- It is undefined behavior for control to transfer from a ``cleanuppad`` to + itself without first executing a ``cleanupret`` that consumes the + ``cleanuppad`` or unwinding out of the ``cleanuppad``. Example: """""""" .. code-block:: llvm - %res = cleanuppad { i8*, i32 } [label %nextaction] + %tok = cleanuppad [] .. _intrinsics: @@ -10741,11 +10762,11 @@ This is an overloaded intrinsic. The loaded data is a vector of any integer bit Overview: """"""""" -The ``llvm.uabsdiff`` intrinsic returns a vector result of the absolute difference of the two operands, -treating them both as unsigned integers. +The ``llvm.uabsdiff`` intrinsic returns a vector result of the absolute difference of +the two operands, treating them both as unsigned integers. -The ``llvm.sabsdiff`` intrinsic returns a vector result of the absolute difference of the two operands, -treating them both as signed integers. +The ``llvm.sabsdiff`` intrinsic returns a vector result of the absolute difference of +the two operands, treating them both as signed integers. .. note::