From: Eli Friedman Date: Wed, 30 Jul 2008 04:36:32 +0000 (+0000) Subject: Another SCEV issue from PR2607; essentially the same issue, but this X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1fbffe0cef92ee284f44cfef3ce0db7ec7d86f18;p=oota-llvm.git Another SCEV issue from PR2607; essentially the same issue, but this time applying to the implicit comparison in smin expressions. The correct way to transform an inequality into the opposite inequality, either signed or unsigned, is with a not expression. I looked through the SCEV code, and I don't think there are any more occurrences of this issue. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54194 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 14c1389b434..bf6bc0b5dc2 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -1789,10 +1789,10 @@ SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) { if (LHS == U->getOperand(1) && RHS == U->getOperand(2)) return SE.getSMaxExpr(getSCEV(LHS), getSCEV(RHS)); else if (LHS == U->getOperand(2) && RHS == U->getOperand(1)) - // -smax(-x, -y) == smin(x, y). - return SE.getNegativeSCEV(SE.getSMaxExpr( - SE.getNegativeSCEV(getSCEV(LHS)), - SE.getNegativeSCEV(getSCEV(RHS)))); + // ~smax(~x, ~y) == smin(x, y). + return SE.getNotSCEV(SE.getSMaxExpr( + SE.getNotSCEV(getSCEV(LHS)), + SE.getNotSCEV(getSCEV(RHS)))); break; case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_ULE: diff --git a/test/Analysis/ScalarEvolution/2008-07-29-SMinExpr.ll b/test/Analysis/ScalarEvolution/2008-07-29-SMinExpr.ll new file mode 100644 index 00000000000..5947912cafe --- /dev/null +++ b/test/Analysis/ScalarEvolution/2008-07-29-SMinExpr.ll @@ -0,0 +1,24 @@ +; RUN: llvm-as < %s | opt -analyze -scalar-evolution -disable-output \ +; RUN: -scalar-evolution-max-iterations=0 | \ +; RUN: grep -F "( -2147483632 + ( 2147483632 smax ( -1 + ( -1 * %x)) smax ( -1 + ( -1 * %y)))) iterations" +; PR2607 + +define i32 @b(i32 %x, i32 %y) { +entry: + %cmp2 = icmp slt i32 %y, %x + %cond3 = select i1 %cmp2, i32 %y, i32 %x + %cmp54 = icmp slt i32 %cond3, -2147483632 + br i1 %cmp54, label %forinc, label %afterfor + +forinc: ; preds = %forinc, %entry + %j.01 = phi i32 [ %dec, %forinc ], [ -2147483632, %entry ] + %dec = add i32 %j.01, -1 + %cmp = icmp slt i32 %y, %x + %cond = select i1 %cmp, i32 %y, i32 %x + %cmp5 = icmp sgt i32 %dec, %cond + br i1 %cmp5, label %forinc, label %afterfor + +afterfor: ; preds = %forinc, %entry + %j.0.lcssa = phi i32 [ -2147483632, %entry ], [ %dec, %forinc ] + ret i32 %j.0.lcssa +}