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More fleshing out of docs/Passes.html, plus some typo fixes and

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improved wording in source files.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43377 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Gordon Henriksen
2007-10-26 03:03:51 +00:00
parent 2bd122c4d9
commit 55cbec317d
4 changed files with 323 additions and 67 deletions
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16
lib/Transforms/IPO/ArgumentPromotion.cpp
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@@ -9,22 +9,22 @@
//
// This pass promotes "by reference" arguments to be "by value" arguments. In
// practice, this means looking for internal functions that have pointer
// arguments. If we can prove, through the use of alias analysis, that an
// argument is *only* loaded, then we can pass the value into the function
// arguments. If it can prove, through the use of alias analysis, that an
// argument is *only* loaded, then it can pass the value into the function
// instead of the address of the value. This can cause recursive simplification
// of code and lead to the elimination of allocas (especially in C++ template
// code like the STL).
//
// This pass also handles aggregate arguments that are passed into a function,
// scalarizing them if the elements of the aggregate are only loaded. Note that
// we refuse to scalarize aggregates which would require passing in more than
// three operands to the function, because we don't want to pass thousands of
// operands for a large array or structure!
// it refuses to scalarize aggregates which would require passing in more than
// three operands to the function, because passing thousands of operands for a
// large array or structure is unprofitable!
//
// Note that this transformation could also be done for arguments that are only
// stored to (returning the value instead), but we do not currently handle that
// case. This case would be best handled when and if we start supporting
// multiple return values from functions.
// stored to (returning the value instead), but does not currently. This case
// would be best handled when and if LLVM begins supporting multiple return
// values from functions.
//
//===----------------------------------------------------------------------===//