https://llvm.org/bugs/show_bug.cgi?id=28665
Bug ID: 28665
Summary: [InstSimplify] missing analysis for bit manipulation
intrinsics
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: spatel+l...@rotateright.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
define i1 @ctlz_cmp_false(i32 %a) {
%x = tail call i32 @llvm.ctlz.i32(i32 %a, i1 false) nounwind readnone
%cmp = icmp ugt i32 %x, 32
ret i1 %cmp
}
define i1 @cttz_cmp_false(i32 %a) {
%x = tail call i32 @llvm.cttz.i32(i32 %a, i1 false) nounwind readnone
%cmp = icmp ugt i32 %x, 32
ret i1 %cmp
}
define i1 @ctpop_cmp_false(i32 %a) {
%x = tail call i32 @llvm.ctpop.i32(i32 %a) nounwind readnone
%cmp = icmp ugt i32 %x, 32
ret i1 %cmp
}
declare i32 @llvm.cttz.i32(i32, i1) nounwind readnone
declare i32 @llvm.ctlz.i32(i32, i1) nounwind readnone
declare i32 @llvm.ctpop.i32(i32) nounwind readnone
-----------------------------------------------------------------------------
$ ./opt -instsimplify bitz.ll -S
(doesn't change anything)
Note that this does work:
define i1 @ctlz_cmp_true(i32 %a) {
%x = tail call i32 @llvm.ctlz.i32(i32 %a, i1 false) nounwind readnone
%cmp = icmp uge i32 %x, 0
ret i1 %cmp
}
$ ./opt -instsimplify bitz.ll -S
...
define i1 @ctlz_cmp_true(i32 %a) {
ret i1 true
}
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