<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Mar 25, 2016, at 2:23 PM, Akira Hatanaka via cfe-commits <<a href="mailto:cfe-commits@lists.llvm.org" class="">cfe-commits@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On Mar 25, 2016, at 2:06 PM, David Majnemer via cfe-commits <<a href="mailto:cfe-commits@lists.llvm.org" class="">cfe-commits@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="gmail_extra"><br class="Apple-interchange-newline"><br class=""><div class="gmail_quote">On Fri, Mar 25, 2016 at 12:57 PM, Akira Hatanaka via cfe-commits<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:cfe-commits@lists.llvm.org" target="_blank" class="">cfe-commits@lists.llvm.org</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;">ahatanak created this revision.<br class="">ahatanak added a reviewer: rjmccall.<br class="">ahatanak added a subscriber: cfe-commits.<br class=""><br class="">r246985 made changes to give a higher alignment for exception objects on the grounds that Itanium says _Unwind_Exception should be "double-word" aligned and the structure is normally declared with __attribute__((aligned)) guaranteeing 16-byte alignment. It turns out that libc++abi doesn't declare the structure with __attribute__((aligned)) and therefore only guarantees 8-byte alignment on 32-bit and 64-bit platforms. This caused a crash in some cases when the backend emitted SIMD store instructions that requires 16-byte alignment (such as movaps).<br class=""><br class="">This patch makes ItaniumCXXABI::getAlignmentOfExnObject return an 8-byte alignment on Darwin to fix the crash.<br class=""><br class=""><a href="http://reviews.llvm.org/D18479" rel="noreferrer" target="_blank" class="">http://reviews.llvm.org/D18479</a><br class=""><br class="">Files:<br class=""> <span class="Apple-converted-space"> </span>lib/CodeGen/ItaniumCXXABI.cpp<br class=""> <span class="Apple-converted-space"> </span>test/CodeGenCXX/eh.cpp<br class=""><br class="">Index: test/CodeGenCXX/eh.cpp<br class="">===================================================================<br class="">--- test/CodeGenCXX/eh.cpp<br class="">+++ test/CodeGenCXX/eh.cpp<br class="">@@ -448,5 +448,27 @@<br class=""> }<br class=""> }<br class=""><br class="">+namespace test17 {<br class="">+class BaseException {<br class="">+private:<br class="">+ int a[4];<br class="">+public:<br class="">+ BaseException() {};<br class="">+};<br class="">+<br class="">+class DerivedException: public BaseException {<br class="">+};<br class="">+<br class="">+int foo() {<br class="">+ throw DerivedException();<br class="">+ // The alignment passed to memset is 8, not 16, on Darwin.<br class="">+<br class="">+ // CHECK: [[T0:%.*]] = call i8* @__cxa_allocate_exception(i64 16)<br class="">+ // CHECK-NEXT: [[T1:%.*]] = bitcast i8* [[T0]] to %"class.test17::DerivedException"*<br class="">+ // CHECK-NEXT: [[T2:%.*]] = bitcast %"class.test17::DerivedException"* [[T1]] to i8*<br class="">+ // CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[T2]], i8 0, i64 16, i32 8, i1 false)<br class="">+}<br class="">+}<br class="">+<br class=""> // CHECK: attributes [[NUW]] = { nounwind }<br class=""> // CHECK: attributes [[NR]] = { noreturn }<br class="">Index: lib/CodeGen/ItaniumCXXABI.cpp<br class="">===================================================================<br class="">--- lib/CodeGen/ItaniumCXXABI.cpp<br class="">+++ lib/CodeGen/ItaniumCXXABI.cpp<br class="">@@ -163,8 +163,17 @@<br class=""> /// we assume that alignment here. (It's generally 16 bytes, but<br class=""> /// some targets overwrite it.)<br class=""> CharUnits getAlignmentOfExnObject() {<br class="">- auto align = CGM.getContext().getTargetDefaultAlignForAttributeAligned();<br class="">- return CGM.getContext().toCharUnitsFromBits(align);<br class="">+ unsigned Align;<br class="">+<br class="">+ // Alignment is 8 for darwin since libc++abi doesn't declare<br class="">+ // _Unwind_Exception with __attribute__((aligned)) and therefore doesn't<br class="">+ // guarantee 16-byte alignment.<br class="">+ if (CGM.getContext().getTargetInfo().getTriple().isOSDarwin())<br class=""></blockquote><div class=""><br class=""></div><div class="">What about Linux/FreeBSD targets which use libc++abi?</div><div class=""> </div></div></div></div></div></blockquote><div class=""><br class=""></div><div class="">Is there a way to detect whether libc++abi is used?</div><br class=""></div></div></blockquote><div><br class=""></div>I wasn’t planning to fix this for Linux or FreeBSD because I don’t know whether that is what people want. If the library being used returns an object that is 16-byte aligned (does libsupc++ return an aligned object?), my change would unnecessarily pessimize the code.</div><div><br class=""><blockquote type="cite" class=""><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;">+ Align = 64;<br class="">+ else<br class="">+ Align = CGM.getContext().getTargetDefaultAlignForAttributeAligned();<br class="">+<br class="">+ return CGM.getContext().toCharUnitsFromBits(Align);<br class=""> }<br class=""><br class=""> void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;<br class=""><br class=""><br class=""><br class="">_______________________________________________<br class="">cfe-commits mailing list<br class=""><a href="mailto:cfe-commits@lists.llvm.org" class="">cfe-commits@lists.llvm.org</a><br class=""><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits" rel="noreferrer" target="_blank" class="">http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits</a><br class=""><br class=""></blockquote></div><br class=""></div></div><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; 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