| author | Arnold Schwaighofer <aschwaighofer@apple.com> | |
| Thu, 2 Jan 2014 03:31:36 +0000 (03:31 +0000) | ||
| committer | Arnold Schwaighofer <aschwaighofer@apple.com> | |
| Thu, 2 Jan 2014 03:31:36 +0000 (03:31 +0000) | ||
| commit | 1bdb320daea95b65bf5a5293132a8911ca1a7524 | |
| tree | cddcf3638496f46dbc431c7b4afda26e49958ac8 | tree | snapshot (tar.xz tar.gz zip) |
| parent | f8735544dc5c75a0b0de7ff13e130ad93d9a1ac1 | commit | diff |
BasicAA: Fix value equality and phi cycles
When there are cycles in the value graph we have to be careful interpreting
"Value*" identity as "value" equivalence. We interpret the value of a phi node
as the value of its operands.
When we check for value equivalence now we make sure that the "Value*" dominates
all cycles (phis).
%0 = phi [%noaliasval, %addr2]
%l = load %ptr
%addr1 = gep @a, 0, %l
%addr2 = gep @a, 0, (%l + 1)
store %ptr ...
Before this patch we would return NoAlias for (%0, %addr1) which is wrong
because the value of the load is from different iterations of the loop.
Tested on x86_64 -mavx at O3 and O3 -flto with no performance or compile time
regressions.
PR18068
radar://15653794
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198290 91177308-0d34-0410-b5e6-96231b3b80d8
When there are cycles in the value graph we have to be careful interpreting
"Value*" identity as "value" equivalence. We interpret the value of a phi node
as the value of its operands.
When we check for value equivalence now we make sure that the "Value*" dominates
all cycles (phis).
%0 = phi [%noaliasval, %addr2]
%l = load %ptr
%addr1 = gep @a, 0, %l
%addr2 = gep @a, 0, (%l + 1)
store %ptr ...
Before this patch we would return NoAlias for (%0, %addr1) which is wrong
because the value of the load is from different iterations of the loop.
Tested on x86_64 -mavx at O3 and O3 -flto with no performance or compile time
regressions.
PR18068
radar://15653794
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198290 91177308-0d34-0410-b5e6-96231b3b80d8