https://llvm.org/bugs/show_bug.cgi?id=27531
Bug ID: 27531
Summary: Shrink-wrapping clobbers live EFLAGS value
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Common Code Generator Code
Assignee: unassignedb...@nondot.org
Reporter: h...@chromium.org
CC: llvm-bugs@lists.llvm.org, qcolom...@apple.com
Classification: Unclassified
a.cc:
struct S {
void foo();
void bar(const int*, double*);
int x_;
};
void S::foo() {
int data[] = { x_ > 32 ? 42 : 128 };
if (x_ <= 31)
return;
double d;
bar(data, &d);
}
Compiled like this:
$ bin/clang -target i686-pc-win32 -Os -S -o - /tmp/a.cc -march=i686
Yields the following output:
"?foo@S@@QAEXXZ": # @"\01?foo@S@@QAEXXZ"
# BB#0: # %entry
cmpl $32, (%ecx)
movl $42, %eax
jg LBB0_2 <---- Sets EFLAGS
# BB#1: # %entry
movl $128, %eax
LBB0_2: # %entry
pushl %ebp
movl %esp, %ebp
andl $-8, %esp <---- Clobbers EFLAGS
leal -16(%esp), %esp
movl %eax, 4(%esp)
jl LBB0_4 <---- Was depending on EFLAGS
# BB#3: # %if.end
leal 8(%esp), %eax
leal 4(%esp), %edx
pushl %eax
pushl %edx
calll "?bar@S@@QAEXPBHPAN@Z"
LBB0_4: # %cleanup
movl %ebp, %esp
popl %ebp
retl
--
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