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Weird code sometimes uses pointer constants other than null. This patch teaches SimplifyCFG to build switch instructions in those cases. Code like this: void f(const char *x) { if (!x) puts("null"); else if ((uintptr_t)x == 1) puts("one"); else if (x == (char*)2 || x == (char*)3) puts("two"); else if ((intptr_t)x == 4) puts("four"); else puts(x); } Now becomes a switch: define void @f(i8* %x) nounwind ssp { entry: %magicptr23 = ptrtoint i8* %x to i64 ; <i64> [#uses=1] switch i64 %magicptr23, label %if.else16 [ i64 0, label %if.then i64 1, label %if.then2 i64 2, label %if.then9 i64 3, label %if.then9 i64 4, label %if.then14 ] Note that LLVM's own DenseMap uses magic pointers. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95439 91177308-0d34-0410-b5e6-96231b3b80d8 |
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