[llvm] acb8de5 - [JumpThreading] Change asserts for WantInteger into actual checks

[Jessica Paquette via llvm-commits]

Author: Jessica Paquette
Date: 2022-01-14T11:15:14-08:00
New Revision: acb8de565eaa2638d18362085085deb4628435b4

URL: https://github.com/llvm/llvm-project/commit/acb8de565eaa2638d18362085085deb4628435b4
DIFF: https://github.com/llvm/llvm-project/commit/acb8de565eaa2638d18362085085deb4628435b4.diff

LOG: [JumpThreading] Change asserts for WantInteger into actual checks

After e734e8286b4b521d829aaddb6d1cbbd264953625, it is possible to end up in
a situation where an `indirectbr` is fed by a cast, which is in turn fed by
an operation which only produces integers.

`indirectbr` expects a block address, however these operations can't produce
that.

There were several asserts in `computeValueKnownInPredecessorsImpl` which check
that we're not looking for a block address if we're walking through something
which can never produce one.

Since it's now possible to hit these asserts, this changes them into actual
checks which return false if `Preference` is not `WantInteger`.

This adds a testcase which verifies that we don't crash anymore in these
situations.

Differential Revision: https://reviews.llvm.org/D99814

Added: 
    llvm/test/Transforms/JumpThreading/indirectbr-cast-int-op.ll

Modified: 
    llvm/lib/Transforms/Scalar/JumpThreading.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index fe9a7211967c..a3efad104ca6 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -728,8 +728,8 @@ bool JumpThreadingPass::computeValueKnownInPredecessorsImpl(
   // Handle some boolean conditions.
   if (I->getType()->getPrimitiveSizeInBits() == 1) {
     using namespace PatternMatch;
-
-    assert(Preference == WantInteger && "One-bit non-integer type?");
+    if (Preference != WantInteger)
+      return false;
     // X | true -> true
     // X & false -> false
     Value *Op0, *Op1;
@@ -789,8 +789,8 @@ bool JumpThreadingPass::computeValueKnownInPredecessorsImpl(
 
   // Try to simplify some other binary operator values.
   } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
-    assert(Preference != WantBlockAddress
-            && "A binary operator creating a block address?");
+    if (Preference != WantInteger)
+      return false;
     if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) {
       PredValueInfoTy LHSVals;
       computeValueKnownInPredecessorsImpl(BO->getOperand(0), BB, LHSVals,
@@ -811,7 +811,8 @@ bool JumpThreadingPass::computeValueKnownInPredecessorsImpl(
 
   // Handle compare with phi operand, where the PHI is defined in this block.
   if (CmpInst *Cmp = dyn_cast<CmpInst>(I)) {
-    assert(Preference == WantInteger && "Compares only produce integers");
+    if (Preference != WantInteger)
+      return false;
     Type *CmpType = Cmp->getType();
     Value *CmpLHS = Cmp->getOperand(0);
     Value *CmpRHS = Cmp->getOperand(1);

diff  --git a/llvm/test/Transforms/JumpThreading/indirectbr-cast-int-op.ll b/llvm/test/Transforms/JumpThreading/indirectbr-cast-int-op.ll
new file mode 100644
index 000000000000..f5555b67f41d
--- /dev/null
+++ b/llvm/test/Transforms/JumpThreading/indirectbr-cast-int-op.ll
@@ -0,0 +1,71 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -jump-threading -S < %s | FileCheck %s
+
+; The indirectbr needs a block address. The add can't produce that.
+; This shouldn't crash.
+define void @cast_with_binop() {
+; CHECK-LABEL: @cast_with_binop(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[OP:%.*]] = add i64 ptrtoint (i8* inttoptr (i32 1 to i8*) to i64), undef
+; CHECK-NEXT:    [[CAST:%.*]] = inttoptr i64 [[OP]] to i8*
+; CHECK-NEXT:    indirectbr i8* [[CAST]], [label [[BB3:%.*]], label %bb2]
+; CHECK:       bb2:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb3:
+; CHECK-NEXT:    ret void
+;
+bb:
+  %op = add i64 ptrtoint (i8* inttoptr (i32 1 to i8*) to i64), undef
+  %cast = inttoptr i64 %op to i8*
+  indirectbr i8* %cast, [label %bb3, label %bb2]
+bb2:
+  unreachable
+bb3:
+  ret void
+}
+
+; The indirectbr needs a block address. The add can't produce that.
+; This shouldn't crash.
+define void @cast_with_i1(i1 %x, i1 %y) {
+; CHECK-LABEL: @cast_with_i1(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[OP:%.*]] = add i1 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[CAST:%.*]] = inttoptr i1 [[OP]] to i8*
+; CHECK-NEXT:    indirectbr i8* [[CAST]], [label [[BB3:%.*]], label %bb2]
+; CHECK:       bb2:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb3:
+; CHECK-NEXT:    ret void
+;
+bb:
+  %op = add i1 %x, %y
+  %cast = inttoptr i1 %op to i8*
+  indirectbr i8* %cast, [label %bb3, label %bb2]
+bb2:
+  unreachable
+bb3:
+  ret void
+}
+
+; The indirectbr needs a block address. The cmp can't produce that.
+; This shouldn't crash.
+define void @cast_with_cmp(i1 %x, i1 %y) {
+; CHECK-LABEL: @cast_with_cmp(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[OP:%.*]] = icmp slt i1 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[CAST:%.*]] = inttoptr i1 [[OP]] to i8*
+; CHECK-NEXT:    indirectbr i8* [[CAST]], [label [[BB3:%.*]], label %bb2]
+; CHECK:       bb2:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb3:
+; CHECK-NEXT:    ret void
+;
+bb:
+  %op = icmp slt i1 %x, %y
+  %cast = inttoptr i1 %op to i8*
+  indirectbr i8* %cast, [label %bb3, label %bb2]
+bb2:
+  unreachable
+bb3:
+  ret void
+}