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From: "balakrishnan.erode at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/53792] [C++11] improving compiler-time constexpr evaluation Date: Wed, 06 May 2015 15:03:00 -0000 [thread overview] Message-ID: <bug-53792-4-cTi1HnMpma@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-53792-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53792 Balakrishnan B <balakrishnan.erode at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |balakrishnan.erode at gmail dot co | |m --- Comment #8 from Balakrishnan B <balakrishnan.erode at gmail dot com> --- Another testcase with c++14 extended constexpr (i.e supports loops and more than one statement). Code: template<class T> void sink(T); constexpr unsigned foo(){ unsigned i = 1; while((i<<1) > i){ i = i<<1; } return i; } template<unsigned i> struct Foo { }; void bar(){ sink(foo()); sink(Foo<foo()>{}); } Assembly for bar: clang3.5.1 -O3 -std=c++14 bar(): # @bar() pushq %rax movl $-2147483648, %edi # imm = 0xFFFFFFFF80000000 callq void sink<unsigned int>(unsigned int) popq %rax jmp void sink<Foo<2147483648u> >(Foo<2147483648u>) # TAILCALL gcc5.1.0 -O3 -std=c++14 bar(): movl $32, %eax movl $1, %edi jmp .L2 .L3: movl %edx, %edi .L2: subl $1, %eax leal (%rdi,%rdi), %edx jne .L3 subq $8, %rsp call void sink<unsigned int>(unsigned int) subq $8, %rsp pushq $0 call void sink<Foo<2147483648u> >(Foo<2147483648u>) addq $24, %rsp ret Live demo: http://goo.gl/b56Q5k
prev parent reply other threads:[~2015-05-06 15:03 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-06-28 6:59 [Bug c++/53792] New: [C++11][constexpr] " vincenzo.innocente at cern dot ch 2012-06-28 9:34 ` [Bug c++/53792] " rguenth at gcc dot gnu.org 2012-06-28 11:08 ` vincenzo.innocente at cern dot ch 2012-07-19 14:28 ` jason at gcc dot gnu.org 2012-07-27 10:48 ` vincenzo.innocente at cern dot ch 2012-07-27 15:06 ` jason at redhat dot com 2012-08-08 11:18 ` giulio.eulisse at cern dot ch 2012-08-08 18:19 ` paolo.carlini at oracle dot com 2015-05-06 15:03 ` balakrishnan.erode at gmail dot com [this message]
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