From 83c05e5d30366d7c7e3d08e886dee89b1320ae7a Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Wed, 3 Sep 2008 05:54:33 +0000
Subject: [PATCH] Don't crash when trying to constant fold a vector with some
 elements that can't be folded. Instead, fail to fold the entire vector.

We could also return a vector with some elements folded and some not. If anyone
thinks that's a better approach, please speak up!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55689 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/ConstantFold.cpp                   | 18 ++++++++-----
 .../InstCombine/2008-09-02-VectorCrash.ll     | 27 +++++++++++++++++++
 2 files changed, 39 insertions(+), 6 deletions(-)
 create mode 100644 test/Transforms/InstCombine/2008-09-02-VectorCrash.ll

diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index 5167c12d49b..25c756ab6e5 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -238,9 +238,12 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
       std::vector<Constant*> res;
       const VectorType *DestVecTy = cast<VectorType>(DestTy);
       const Type *DstEltTy = DestVecTy->getElementType();
-      for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
-        res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i),
-                                                  DstEltTy));
+      for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) {
+        Constant *C = ConstantFoldCastInstruction(opc, CV->getOperand(i),
+                                                  DstEltTy);
+        if (!C) return 0;       // Can't fold operand.
+        res.push_back(C);
+      }
       return ConstantVector::get(DestVecTy, res);
     }
     return 0; // Can't fold.
@@ -268,9 +271,12 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
       std::vector<Constant*> res;
       const VectorType *DestVecTy = cast<VectorType>(DestTy);
       const Type *DstEltTy = DestVecTy->getElementType();
-      for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
-        res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i),
-                                                  DstEltTy));
+      for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) {
+        Constant *C = ConstantFoldCastInstruction(opc, CV->getOperand(i),
+                                                  DstEltTy);
+        if (!C) return 0;       // Can't fold operand.
+        res.push_back(C);
+      }
       return ConstantVector::get(DestVecTy, res);
     }
     return 0;
diff --git a/test/Transforms/InstCombine/2008-09-02-VectorCrash.ll b/test/Transforms/InstCombine/2008-09-02-VectorCrash.ll
new file mode 100644
index 00000000000..4b5dc6a5dfc
--- /dev/null
+++ b/test/Transforms/InstCombine/2008-09-02-VectorCrash.ll
@@ -0,0 +1,27 @@
+; RUN: llvm-as < %s | opt -instcombine
+
+define void @entry(i32 %m_task_id, i32 %start_x, i32 %end_x, i32 %start_y, i32 %end_y) {
+	br label %1
+
+; <label>:1		; preds = %4, %0
+	%2 = icmp slt i32 0, %end_y		; <i1> [#uses=1]
+	br i1 %2, label %4, label %3
+
+; <label>:3		; preds = %1
+	ret void
+
+; <label>:4		; preds = %6, %1
+	%5 = icmp slt i32 0, %end_x		; <i1> [#uses=1]
+	br i1 %5, label %6, label %1
+
+; <label>:6		; preds = %4
+	%7 = srem <2 x i32> zeroinitializer, zeroinitializer		; <<2 x i32>> [#uses=1]
+	%8 = extractelement <2 x i32> %7, i32 1		; <i32> [#uses=1]
+	%9 = select i1 false, i32 0, i32 %8		; <i32> [#uses=1]
+	%10 = insertelement <2 x i32> zeroinitializer, i32 %9, i32 1		; <<2 x i32>> [#uses=1]
+	%11 = extractelement <2 x i32> %10, i32 1		; <i32> [#uses=1]
+	%12 = insertelement <4 x i32> zeroinitializer, i32 %11, i32 3		; <<4 x i32>> [#uses=1]
+	%13 = sitofp <4 x i32> %12 to <4 x float>		; <<4 x float>> [#uses=1]
+	store <4 x float> %13, <4 x float>* null
+	br label %4
+}
-- 
2.34.1