From 6509f50c69b26b88a77bcae6b9ba84c7e6122b73 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Tue, 11 Oct 2011 23:01:39 +0000 Subject: improve some of the documentation around target data layout strings. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141733 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/LangRef.html | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'docs') diff --git a/docs/LangRef.html b/docs/LangRef.html index 145c19f3e5..8e54f3c433 100644 --- a/docs/LangRef.html +++ b/docs/LangRef.html @@ -1406,6 +1406,22 @@ target datalayout = "layout specification" implemented in terms of 64 <2 x double>, for example. +

The function of the data layout string may not be what you expect. Notably, + this is not a specification from the frontend of what alignment the code + generator should use.

+ +

Instead, if specified, the target data layout is required to match what the + ultimate code generator expects. This string is used by the + mid-level optimizers to + improve code, and this only works if it matches what the ultimate code + generator uses. If you would like to generate IR that does not embed this + target-specific detail into the IR, then you don't have to specify the + string. This will disable some optimizations that require precise layout + information, but this also prevents those optimizations from introducing + target specificity into the IR.

+ + + -- cgit v1.2.3