https://bugs.llvm.org/show_bug.cgi?id=35241
Bug ID: 35241
Summary: 'Undefined behavior: Call with "tail" keyword
references alloca' after memcpyopt
Product: new-bugs
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: mikael.hol...@ericsson.com
CC: llvm-bugs@lists.llvm.org
Created attachment 19382
--> https://bugs.llvm.org/attachment.cgi?id=19382&action=edit
reproducer
opt -memcpyopt -lint -S -o tr14894.opt.ll tr14894.ll
makes lint complain with
Undefined behavior: Call with "tail" keyword references alloca
tail call void @f1(%s* byval align 1 %c)
memcpyopt has turned
%tmp1 = bitcast %s* %c to i8*
%tmp2 = bitcast i8* bitcast (%s* @b to i8*) to i8*
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp2, i8* %tmp1, i32 3, i32 1, i1
false)
tail call void @f1(%s* byval align 1 @b)
into
%tmp1 = bitcast %s* %c to i8*
%tmp2 = bitcast i8* getelementptr inbounds (%s, %s* @b, i32 0, i32 0) to i8*
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp2, i8* %tmp1, i32 3, i32 1, i1
false)
tail call void @f1(%s* byval align 1 %c)
Should memcpyopt avoid th transformation for tail calls perhaps?
(Or is the lint warning in fact wrong for byval arguments?)
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