[SCEVExp] Advance found insertion point until we find a non-dbg instr…

…uction.

This avoids creating unnecessary casts if the IP used to be a dbg info
intrinsic. Fixes PR37727.

Reviewers: vsk, aprantl, sanjoy, efriedma

Reviewed By: vsk, efriedma

Differential Revision: https://reviews.llvm.org/D47874

llvm-svn: 335513

llvm/lib/Analysis/ScalarEvolutionExpander.cpp

@@ -162,7 +162,8 @@ Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
 
   // Cast the instruction immediately after the instruction.
   Instruction *I = cast<Instruction>(V);
-  BasicBlock::iterator IP = findInsertPointAfter(I, Builder.GetInsertBlock());
+  BasicBlock::iterator IP = skipDebugInfo(
+      findInsertPointAfter(I, Builder.GetInsertBlock()));
   return ReuseOrCreateCast(I, Ty, Op, IP);
 }
 
@@ -1480,8 +1481,8 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
       NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
     Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
                                        S->getNoWrapFlags(SCEV::FlagNW)));
-    BasicBlock::iterator NewInsertPt =
-        findInsertPointAfter(cast<Instruction>(V), Builder.GetInsertBlock());
+    BasicBlock::iterator NewInsertPt = skipDebugInfo(
+        findInsertPointAfter(cast<Instruction>(V), Builder.GetInsertBlock()));
     V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), nullptr,
                       &*NewInsertPt);
     return V;

llvm/test/Transforms/LoopVectorize/scev-expander-debug.ll

@@ -0,0 +1,61 @@
+; RUN: opt -loop-vectorize %s -S | FileCheck %s
+; Tests that the debug intrinsic does not cause additional instructions to be
+; created by SCEVExpander.
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.s = type { double* }
+
+; CHECK-LABEL: entry:
+; CHECK: %[[LV:.+]] = load double*, double** %a
+; CHECK-NEXT: call void @llvm.dbg.value(metadata double* %[[LV]]
+; CHECK-NEXT: %[[PTI:.+]] = ptrtoint double* %[[LV]] to i64
+; CHECK-NEXT: %[[MPTR:.+]] = and i64 %[[PTI]], 31
+; CHECK-NEXT: %[[MCOND:.+]] = icmp eq i64 %[[MPTR]], 0
+; CHECK-NEXT: br i1 false, label %scalar.ph, label %vector.scevcheck
+
+
+define void @test(%struct.s* %x) !dbg !6 {
+entry:
+  %a = getelementptr inbounds %struct.s, %struct.s* %x, i64 0, i32 0
+  %0 = load double*, double** %a, align 8
+  call void @llvm.dbg.value(metadata double* %0, metadata !9, metadata !DIExpression()), !dbg !11
+  %ptrint = ptrtoint double* %0 to i64
+  %maskedptr = and i64 %ptrint, 31
+  %maskcond = icmp eq i64 %maskedptr, 0
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next.1, %for.body ]
+  %arrayidx = getelementptr inbounds double, double* %0, i64 %indvars.iv
+  %1 = load double, double* %arrayidx, align 16
+  %add = fadd double %1, 1.000000e+00
+  store double %add, double* %arrayidx, align 16
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %arrayidx.1 = getelementptr inbounds double, double* %0, i64 %indvars.iv.next
+  %2 = load double, double* %arrayidx.1, align 8
+  %add.1 = fadd double %2, 1.000000e+00
+  store double %add.1, double* %arrayidx.1, align 8
+  %indvars.iv.next.1 = add nuw nsw i64 %indvars.iv.next, 1
+  %exitcond.1 = icmp eq i64 %indvars.iv.next, 1599
+  br i1 %exitcond.1, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "file.ll", directory: "/")
+!2 = !{}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "test", linkageName: "test", scope: null, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: true, unit: !0)
+!7 = !DISubroutineType(types: !2)
+!9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
+!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!11 = !DILocation(line: 1, column: 1, scope: !6)