https://llvm.org/bugs/show_bug.cgi?id=31368
Bug ID: 31368
Summary: [Scalar] alignTo is not optimized if alignment is a
power of 2
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: dav...@freebsd.org
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
This came up as part of https://reviews.llvm.org/D27082
Testcase by Rafael.
uint64_t foo(uint64_t Value, uint64_t Align) {
return alignToNonP2(Value, 1 << Align);
}
but it still produces
define i64 @_Z3foomm(i64 %Value, i64 %Align) local_unnamed_addr #0 {
entry:
%sh_prom = trunc i64 %Align to i32
%shl = shl i32 1, %sh_prom
%conv = sext i32 %shl to i64
%add.i = add i64 %Value, -1
%sub.i = add i64 %add.i, %conv
%div.i = urem i64 %sub.i, %conv
%add2.i = sub i64 %sub.i, %div.i
ret i64 %add2.i
}
Changing 1 to 1ULL does cause us to optimize it
define i64 @_Z3foomm(i64 %Value, i64 %Align) local_unnamed_addr #0 {
entry:
%shl = shl i64 1, %Align
%add.i = add i64 %Value, -1
%sub.i = add i64 %add.i, %shl
%.not = sub i64 0, %shl
%add2.i = and i64 %sub.i, %.not
ret i64 %add2.i
}
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