https://bugs.llvm.org/show_bug.cgi?id=36042
Bug ID: 36042
Summary: [PCG] Redundant stack operations
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: konstantin.belocha...@sony.com
CC: llvm-bugs@lists.llvm.org
Redundant stack operations from clang.
A repro case with command line and disassembly is below.
Source (test.c):
typedef bool (*CallbackFunc)(unsigned int param);
bool Test(CallbackFunc func, unsigned int param)
{
bool x = func(param);
return (x || 1);
}
Command Line:
clang -fomit-frame-pointer -O2 -g -c test.c test.o
Disassembly:
Test: # @Test
.cfi_startproc
# BB#0: # %entry
pushq %rax
.Ltmp1:
.cfi_def_cfa_offset 16
movq %rdi, %rax
movl %esi, %edi
callq *%rax
movb $1, %al
popq %rdx
ret
Notice the redundant 'push rax' (and the 'pop rdx' that seems to go with it).
Please note that the -fomit-frame-pointer is intentional in this
case, btw.. even though it's not actually a leaf function.
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