Summary:
The "=r" output constraint for a structure variable passed to inline asm
shouldn't be converted to "=*r", as this changes the asm directive
semantics and prevents DSE optimizations.
Instead, preserve the constraints and return such structures as integers
of corresponding size, which are converted back to structures when
storing the result.
Fixes PR42672.
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D65234
llvm-svn: 370335
Previously, clang/llvm treated inline-asm instructions conservatively,
choosing not to eliminate the instructions or hoisting them out of a loop
even when it was safe to do so. This commit makes changes to attach a
readonly or readnone attribute to an inline-asm instruction, which enables
passes such as LICM and EarlyCSE to move or optimize away the instruction.
rdar://problem/11358192
Differential Revision: http://reviews.llvm.org/D10546
llvm-svn: 241930
Alexander Potapenko