<div dir="ltr">clang has the same template specialization defined in clang/lib/Basic/VirtualFileSystem.cpp.<div><br><div class="gmail_quote"><div dir="ltr">On Wed, Jun 24, 2015 at 12:13 PM Chandler Carruth <<a href="mailto:chandlerc@gmail.com" target="_blank">chandlerc@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: chandlerc<br>
Date: Wed Jun 24 05:06:29 2015<br>
New Revision: 240528<br>
<br>
URL: <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D240528-26view-3Drev&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=oQT7s5alWlBbXpHIo_4fbWpa-1SvotqNTEY_pjpCPF0&s=JqYz8IFCFpRrP0EQrxziB7MloNwo3QkVxtMATjOsgek&e=" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=240528&view=rev</a><br>
Log:<br>
[ADT] Teach DenseMap to support StringRef keys.<br>
<br>
While often you want to use something specialized like StringMap, when<br>
the strings already have persistent storage a normal densemap over them<br>
can be more efficient.<br>
<br>
This can't go into StringRef.h because of really obnoxious header chains<br>
from the hashing code to the endian detection code to CPU feature<br>
detection code to StringMap.<br>
<br>
Modified:<br>
llvm/trunk/include/llvm/ADT/DenseMapInfo.h<br>
llvm/trunk/unittests/ADT/DenseMapTest.cpp<br>
<br>
Modified: llvm/trunk/include/llvm/ADT/DenseMapInfo.h<br>
URL: <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_include_llvm_ADT_DenseMapInfo.h-3Frev-3D240528-26r1-3D240527-26r2-3D240528-26view-3Ddiff&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=oQT7s5alWlBbXpHIo_4fbWpa-1SvotqNTEY_pjpCPF0&s=vECCZPZJAuUq1EvQhWrHdnU3phjnPKcDdJwdP-vzVxw&e=" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/DenseMapInfo.h?rev=240528&r1=240527&r2=240528&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/include/llvm/ADT/DenseMapInfo.h (original)<br>
+++ llvm/trunk/include/llvm/ADT/DenseMapInfo.h Wed Jun 24 05:06:29 2015<br>
@@ -14,6 +14,8 @@<br>
#ifndef LLVM_ADT_DENSEMAPINFO_H<br>
#define LLVM_ADT_DENSEMAPINFO_H<br>
<br>
+#include "llvm/ADT/Hashing.h"<br>
+#include "llvm/ADT/StringRef.h"<br>
#include "llvm/Support/PointerLikeTypeTraits.h"<br>
#include "llvm/Support/type_traits.h"<br>
<br>
@@ -163,6 +165,31 @@ struct DenseMapInfo<std::pair<T, U> > {<br>
}<br>
};<br>
<br>
+// Provide DenseMapInfo for StringRefs.<br>
+template <> struct DenseMapInfo<StringRef> {<br>
+ static inline StringRef getEmptyKey() {<br>
+ return StringRef(reinterpret_cast<const char *>(~static_cast<uintptr_t>(0)),<br>
+ 0);<br>
+ }<br>
+ static inline StringRef getTombstoneKey() {<br>
+ return StringRef(reinterpret_cast<const char *>(~static_cast<uintptr_t>(1)),<br>
+ 0);<br>
+ }<br>
+ static unsigned getHashValue(StringRef Val) {<br>
+ assert(Val.data() != getEmptyKey().data() && "Cannot hash the empty key!");<br>
+ assert(Val.data() != getTombstoneKey().data() &&<br>
+ "Cannot hash the tombstone key!");<br>
+ return (unsigned)(hash_value(Val));<br>
+ }<br>
+ static bool isEqual(StringRef LHS, StringRef RHS) {<br>
+ if (RHS.data() == getEmptyKey().data())<br>
+ return LHS.data() == getEmptyKey().data();<br>
+ if (RHS.data() == getTombstoneKey().data())<br>
+ return LHS.data() == getTombstoneKey().data();<br>
+ return LHS == RHS;<br>
+ }<br>
+};<br>
+<br>
} // end namespace llvm<br>
<br>
#endif<br>
<br>
Modified: llvm/trunk/unittests/ADT/DenseMapTest.cpp<br>
URL: <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_unittests_ADT_DenseMapTest.cpp-3Frev-3D240528-26r1-3D240527-26r2-3D240528-26view-3Ddiff&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=oQT7s5alWlBbXpHIo_4fbWpa-1SvotqNTEY_pjpCPF0&s=IUeocYBq_1H6HxW8lTSFcoId6XO21Uzwu-skf9d6gGg&e=" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/DenseMapTest.cpp?rev=240528&r1=240527&r2=240528&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/unittests/ADT/DenseMapTest.cpp (original)<br>
+++ llvm/trunk/unittests/ADT/DenseMapTest.cpp Wed Jun 24 05:06:29 2015<br>
@@ -323,6 +323,31 @@ TYPED_TEST(DenseMapTest, ConstIteratorTe<br>
EXPECT_TRUE(cit == cit2);<br>
}<br>
<br>
+// Make sure DenseMap works with StringRef keys.<br>
+TEST(DenseMapCustomTest, StringRefTest) {<br>
+ DenseMap<StringRef, int> M;<br>
+<br>
+ M["a"] = 1;<br>
+ M["b"] = 2;<br>
+ M["c"] = 3;<br>
+<br>
+ EXPECT_EQ(3u, M.size());<br>
+ EXPECT_EQ(1, M.lookup("a"));<br>
+ EXPECT_EQ(2, M.lookup("b"));<br>
+ EXPECT_EQ(3, M.lookup("c"));<br>
+<br>
+ EXPECT_EQ(0, M.lookup("q"));<br>
+<br>
+ // Test the empty string, spelled various ways.<br>
+ EXPECT_EQ(0, M.lookup(""));<br>
+ EXPECT_EQ(0, M.lookup(StringRef()));<br>
+ EXPECT_EQ(0, M.lookup(StringRef("a", 0)));<br>
+ M[""] = 42;<br>
+ EXPECT_EQ(42, M.lookup(""));<br>
+ EXPECT_EQ(42, M.lookup(StringRef()));<br>
+ EXPECT_EQ(42, M.lookup(StringRef("a", 0)));<br>
+}<br>
+<br>
// Key traits that allows lookup with either an unsigned or char* key;<br>
// In the latter case, "a" == 0, "b" == 1 and so on.<br>
struct TestDenseMapInfo {<br>
<br>
<br>
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</blockquote></div></div></div>