[LoopDeletion] Clear SCEV loop dispositions

`Loop::makeLoopInvariant` can hoist instructions out of loops, so loop
dispositions for the loop it operated on may need to be cleared.  We can
be smarter here (especially around how `forgetLoopDispositions` is
implemented), but let's be correct first.

Fixes PR27570.

llvm-svn: 268406

1 files changed, 56 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopDeletion/update-scev.ll b/llvm/test/Transforms/LoopDeletion/update-scev.ll
new file mode 100644
index 00000000000..641ba55ed8f
--- /dev/null
+++ b/llvm/test/Transforms/LoopDeletion/update-scev.ll
@@ -0,0 +1,56 @@
+; RUN: opt -S -analyze -scalar-evolution -loop-deletion -scalar-evolution < %s | FileCheck %s --check-prefix=SCEV-EXPRS
+; RUN: opt -S -loop-deletion < %s | FileCheck %s --check-prefix=IR-AFTER-TRANSFORM
+; RUN: opt -S -indvars -loop-deletion -indvars < %s | FileCheck %s --check-prefix=ORIGINAL-CRASH
+
+; Checking for a crash.  Loop-deletion would change the loop
+; disposition of an instruction, but not update SCEV.
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.11.0"
+
+define void @pr27570() {
+; IR-AFTER-TRANSFORM-LABEL: @pr27570(
+; ORIGINAL-CRASH: @pr27570(
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond14, %entry
+  %f.0 = phi i32 [ 20, %entry ], [ 0, %for.cond14 ]
+  br label %for.body
+
+for.body:                                         ; preds = %for.inc11, %for.cond
+; IR-AFTER-TRANSFORM: for.body:
+; IR-AFTER-TRANSFORM: %cmp = icmp eq i32 %val, -1
+; IR-AFTER-TRANSFORM: %conv7 = zext i1 %cmp to i32
+; IR-AFTER-TRANSFORM: for.body6:
+
+; SCEV-EXPRS:  %conv7 = zext i1 %cmp to i32
+; SCEV-EXPRS:  %conv7 = zext i1 %cmp to i32
+; SCEV-EXPRS-NEXT:  -->  {{.*}} LoopDispositions: { %for.body: Variant, %for.cond: Variant, %for.body6: Invariant }
+  %val = phi i32 [ -20, %for.cond ], [ %inc12, %for.inc11 ]
+  %g.040 = phi i32 [ -20, %for.cond ], [ %and.lcssa, %for.inc11 ]
+  br label %for.body6
+
+for.body6:                                        ; preds = %for.body6, %for.body
+  %h.039 = phi i32 [ 1, %for.body ], [ %inc, %for.body6 ]
+  %g.138 = phi i32 [ %g.040, %for.body ], [ %and, %for.body6 ]
+  %cmp = icmp eq i32 %val, -1
+  %conv7 = zext i1 %cmp to i32
+  %add.i = add nsw i32 %conv7, %h.039
+  %sext = shl i32 %add.i, 24
+  %conv8 = ashr exact i32 %sext, 24
+  %cmp9 = icmp eq i32 %conv8, %f.0
+  %conv10 = zext i1 %cmp9 to i32
+  %and = and i32 %conv10, %g.138
+  %inc = add i32 %h.039, 1
+  br i1 undef, label %for.inc11, label %for.body6
+
+for.inc11:                                        ; preds = %for.body6
+  %and.lcssa = phi i32 [ %and, %for.body6 ]
+  %inc12 = add nsw i32 %val, 1
+  %tobool = icmp eq i32 %inc12, 0
+  br i1 %tobool, label %for.cond14, label %for.body
+
+for.cond14:                                       ; preds = %for.cond14, %for.inc11
+  br i1 undef, label %for.cond, label %for.cond14
+}