From 0f139b4f7164302d5e654dc2b243bb2e2fb1ddfc Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Fri, 4 Nov 2016 06:54:00 +0000 Subject: [PATCH] Hoist check for TLI above all of the attempts to use it (including one of which that is hidden inside a separate function call) and helpfully before building expensive transaction infrastructure. This will avoid crashing when running CGP in a generic mode if we ever managed to hit this case. Note that I spent some time looking at alternatives. CGP is actually used without a TM or TLI in order to do some target-independent testing. Further, all of the neighboring optimization techniques actually have some paths that are effective even in the absence of TLI so this seemed the correct scope at which to check and bypass logic. It still isn't clear that long-term support for missing TM/TLI is the right cost/benefit tradeoff for CGP -- we seem to get relatively little for it and the code is just littered with checks (and assumptions which I suspect are still missing some checks). This at least fixes the potential bug in this code spotted by PVS-Studio, so we've got that going for us. ;] llvm-svn: 285987 --- llvm/lib/CodeGen/CodeGenPrepare.cpp | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp index d102ccb..be1e526 100644 --- a/llvm/lib/CodeGen/CodeGenPrepare.cpp +++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp @@ -4232,6 +4232,10 @@ bool CodeGenPrepare::extLdPromotion(TypePromotionTransaction &TPT, /// promotions apply. /// bool CodeGenPrepare::moveExtToFormExtLoad(Instruction *&I) { + // ExtLoad formation infrastructure requires TLI to be effective. + if (!TLI) + return false; + // Try to promote a chain of computation if it allows to form // an extended load. TypePromotionTransaction TPT; @@ -4261,7 +4265,7 @@ bool CodeGenPrepare::moveExtToFormExtLoad(Instruction *&I) { // If the load has other users and the truncate is not free, this probably // isn't worthwhile. - if (!LI->hasOneUse() && TLI && + if (!LI->hasOneUse() && (TLI->isTypeLegal(LoadVT) || !TLI->isTypeLegal(VT)) && !TLI->isTruncateFree(I->getType(), LI->getType())) { I = OldExt; @@ -4277,7 +4281,7 @@ bool CodeGenPrepare::moveExtToFormExtLoad(Instruction *&I) { assert(isa(I) && "Unexpected ext type!"); LType = ISD::SEXTLOAD; } - if (TLI && !TLI->isLoadExtLegal(LType, VT, LoadVT)) { + if (!TLI->isLoadExtLegal(LType, VT, LoadVT)) { I = OldExt; TPT.rollback(LastKnownGood); return false; -- 2.7.4