From 4b476488baeb5216a46e51bcdff0c8de366260a5 Mon Sep 17 00:00:00 2001 From: John Brawn Date: Mon, 27 Nov 2017 11:29:15 +0000 Subject: [CGP] Fix handling of null pointer values in optimizeMemoryInst The current way that trivial addressing modes are detected incorrectly thinks that null pointers are non-trivial, leading to an infinite loop where we keep duplicating the same select. Fix this by aware of null when deciding if an addressing mode is trivial. Differential Revision: https://reviews.llvm.org/D40447 llvm-svn: 319019 --- llvm/lib/CodeGen/CodeGenPrepare.cpp | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) (limited to 'llvm/lib/CodeGen/CodeGenPrepare.cpp') diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp index 64c5db9b560..75f9f81c112 100644 --- a/llvm/lib/CodeGen/CodeGenPrepare.cpp +++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp @@ -2080,16 +2080,14 @@ struct ExtAddrMode : public TargetLowering::AddrMode { return static_cast(Result); } - // AddrModes with a baseReg or gv where the reg/gv is - // the only populated field are trivial. + // An AddrMode is trivial if it involves no calculation i.e. it is just a base + // with no offset. bool isTrivial() { - if (BaseGV && !BaseOffs && !Scale && !BaseReg) - return true; - - if (!BaseGV && !BaseOffs && !Scale && BaseReg) - return true; - - return false; + // An AddrMode is (BaseGV + BaseReg + BaseOffs + ScaleReg * Scale) so it is + // trivial if at most one of these terms is nonzero, except that BaseGV and + // BaseReg both being zero actually means a null pointer value, which we + // consider to be 'non-zero' here. + return !BaseOffs && !Scale && !(BaseGV && BaseReg); } Value *GetFieldAsValue(FieldName Field, Type *IntPtrTy) { -- cgit v1.2.3