Refactor string encoding checks in BitcodeWriter (NFC)

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

diff --git a/docs/BranchWeightMetadata.rst b/docs/BranchWeightMetadata.rst
index aff7923d18656d4531208c9e0afefabf8fbc0a11..6cbcb0f0fb241e12a7dabdc2eb20ac0b3090dcbc 100644 (file)
--- a/docs/BranchWeightMetadata.rst
+++ b/docs/BranchWeightMetadata.rst
@@ -27,7 +27,7 @@ Supported Instructions
 ^^^^^^^^^^^^^^
 
 Metadata is only assigned to the conditional branches. There are two extra
 ^^^^^^^^^^^^^^
 
 Metadata is only assigned to the conditional branches. There are two extra

-operarands for the true and the false branch.
+operands for the true and the false branch.

 
 .. code-block:: llvm
 
 
 .. code-block:: llvm
 


@@ -114,4 +114,27 @@ CFG Modifications
 
 Branch Weight Metatada is not proof against CFG changes. If terminator operands'
 are changed some action should be taken. In other case some misoptimizations may
 
 Branch Weight Metatada is not proof against CFG changes. If terminator operands'
 are changed some action should be taken. In other case some misoptimizations may

-occur due to incorrent branch prediction information.
+occur due to incorrect branch prediction information.
+
+Function Entry Counts
+=====================
+
+To allow comparing different functions during inter-procedural analysis and
+optimization, ``MD_prof`` nodes can also be assigned to a function definition.
+The first operand is a string indicating the name of the associated counter.
+
+Currently, one counter is supported: "function_entry_count". This is a 64-bit
+counter that indicates the number of times that this function was invoked (in
+the case of instrumentation-based profiles). In the case of sampling-based
+profiles, this counter is an approximation of how many times the function was
+invoked.
+
+For example, in the code below, the instrumentation for function foo()
+indicates that it was called 2,590 times at runtime.
+
+.. code-block:: llvm
+
+  define i32 @foo() !prof !1 {
+    ret i32 0
+  }
+  !1 = !{!"function_entry_count", i64 2590}