From 55312debee5c3f224cd36913d4a00a6ce91676c5 Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Wed, 2 Apr 2014 23:18:54 +0000 Subject: Fix multi-register costs in BasicTTI::getCastInstrCost For an cast (extension, etc.), the currently logic predicts a low cost if the associated operation (keyed on the destination type) is legal (or promoted). This is not true when the number of values required to legalize the type is changing. For example, <8 x i16> being sign extended by <8 x i32> is not generically cheap on PPC with VSX, even though sign extension to v4i32 is legal, because two output v4i32 values are required compared to the single v8i16 input value, and without custom logic in the target, this conversion will scalarize. llvm-svn: 205487 --- llvm/lib/CodeGen/BasicTargetTransformInfo.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'llvm/lib') diff --git a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp index 03c5eba3692..25486cf3919 100644 --- a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp +++ b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp @@ -297,7 +297,8 @@ unsigned BasicTTI::getCastInstrCost(unsigned Opcode, Type *Dst, return 0; // If the cast is marked as legal (or promote) then assume low cost. - if (TLI->isOperationLegalOrPromote(ISD, DstLT.second)) + if (SrcLT.first == DstLT.first && + TLI->isOperationLegalOrPromote(ISD, DstLT.second)) return 1; // Handle scalar conversions. -- cgit v1.2.3