diff --git a/llvm/docs/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack.md b/llvm/docs/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack.md --- a/llvm/docs/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack.md +++ b/llvm/docs/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack/AMDGPUDwarfExtensionAllowLocationDescriptionOnTheDwarfExpressionStack.md @@ -3,7 +3,7 @@ - [Extension](#extension) - [Heterogeneous Computing Devices](#heterogeneous-computing-devices) - [DWARF 5](#dwarf-5) - - [What is DWARF?](#what-is-dwarf) + - [How DWARF Maps Source Language To Hardware](#how-dwarf-maps-source-language-to-hardware) - [Examples](#examples) - [Dynamic Array Size](#dynamic-array-size) - [Variable Location in Register](#variable-location-in-register) @@ -29,15 +29,22 @@ # Extension -This extension is to generalize the DWARF expression evaluation model to allow -location descriptions to be manipulated on the stack. It is done in a manner -that is backwards compatible with DWARF 5. This permits operations to act on -location descriptions in an incremental, consistent, and composable manner. - -It allows a small number of operations to be defined to address the requirements -of heterogeneous devices as well as providing benefits to non-heterogeneous -devices. It also acts as a foundation to provide support for other issues that -have been raised that would benefit all devices. +In DWARF 5, expressions are evaluated using a typed value stack, a separate +location area, and an independent loclist mechanism. This extension unifies all +three mechanisms into a single generalized DWARF expression evaluation model +that allows both typed values and location descriptions to be manipulated on the +evaluation stack. Both single and multiple location descriptions are supported +on the stack. In addition, the call frame information (CFI) is extended to +support the full generality of location descriptions. This is done in a manner +that is backwards compatible with DWARF 5. The extension involves changes to the +DWARF 5 sections 2.5 (pp 26-38), 2.6 (pp 38-45), and 6.4 (pp 171-182). + +The extension permits operations to act on location descriptions in an +incremental, consistent, and composable manner. It allows a small number of +operations to be defined to address the requirements of heterogeneous devices as +well as providing benefits to non-heterogeneous devices. It acts as a foundation +to provide support for other issues that have been raised that would benefit all +devices. Other approaches were explored that involved adding specialized operations and rules. However, these resulted in the need for more operations that did not @@ -100,7 +107,7 @@ brief overview of the DWARF 5 expression evaluation model will be given to highlight the aspects being addressed by the extension. -## What is DWARF? +## How DWARF Maps Source Language To Hardware DWARF is a standardized way to specify debug information. It describes source language entities such as compilation units, functions, types, variables, etc.