[llvm] r358192 - [ConstantFold] ExtractConstantBytes - handle shifts on large integer types

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Thu Apr 11 09:39:31 2019
New Revision: 358192

URL: http://llvm.org/viewvc/llvm-project?rev=358192&view=rev
Log:
[ConstantFold] ExtractConstantBytes - handle shifts on large integer types

Use APInt instead of getZExtValue from the ConstantInt until we can confirm that the shift amount is in range.

Reduced from OSS-Fuzz #14169 - https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14169

Added:
    llvm/trunk/test/Transforms/InstCombine/constant-fold-shifts.ll
Modified:
    llvm/trunk/lib/IR/ConstantFold.cpp

Modified: llvm/trunk/lib/IR/ConstantFold.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/ConstantFold.cpp?rev=358192&r1=358191&r2=358192&view=diff
==============================================================================
--- llvm/trunk/lib/IR/ConstantFold.cpp (original)
+++ llvm/trunk/lib/IR/ConstantFold.cpp Thu Apr 11 09:39:31 2019
@@ -268,19 +268,20 @@ static Constant *ExtractConstantBytes(Co
     ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1));
     if (!Amt)
       return nullptr;
-    unsigned ShAmt = Amt->getZExtValue();
+    APInt ShAmt = Amt->getValue();
     // Cannot analyze non-byte shifts.
     if ((ShAmt & 7) != 0)
       return nullptr;
-    ShAmt >>= 3;
+    ShAmt.lshrInPlace(3);
 
     // If the extract is known to be all zeros, return zero.
-    if (ByteStart >= CSize-ShAmt)
-      return Constant::getNullValue(IntegerType::get(CE->getContext(),
-                                                     ByteSize*8));
+    if (ShAmt.uge(CSize - ByteStart))
+      return Constant::getNullValue(
+          IntegerType::get(CE->getContext(), ByteSize * 8));
     // If the extract is known to be fully in the input, extract it.
-    if (ByteStart+ByteSize+ShAmt <= CSize)
-      return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize);
+    if (ShAmt.ule(CSize - (ByteStart + ByteSize)))
+      return ExtractConstantBytes(CE->getOperand(0),
+                                  ByteStart + ShAmt.getZExtValue(), ByteSize);
 
     // TODO: Handle the 'partially zero' case.
     return nullptr;
@@ -290,19 +291,20 @@ static Constant *ExtractConstantBytes(Co
     ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1));
     if (!Amt)
       return nullptr;
-    unsigned ShAmt = Amt->getZExtValue();
+    APInt ShAmt = Amt->getValue();
     // Cannot analyze non-byte shifts.
     if ((ShAmt & 7) != 0)
       return nullptr;
-    ShAmt >>= 3;
+    ShAmt.lshrInPlace(3);
 
     // If the extract is known to be all zeros, return zero.
-    if (ByteStart+ByteSize <= ShAmt)
-      return Constant::getNullValue(IntegerType::get(CE->getContext(),
-                                                     ByteSize*8));
+    if (ShAmt.uge(ByteStart + ByteSize))
+      return Constant::getNullValue(
+          IntegerType::get(CE->getContext(), ByteSize * 8));
     // If the extract is known to be fully in the input, extract it.
-    if (ByteStart >= ShAmt)
-      return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize);
+    if (ShAmt.ule(ByteStart))
+      return ExtractConstantBytes(CE->getOperand(0),
+                                  ByteStart - ShAmt.getZExtValue(), ByteSize);
 
     // TODO: Handle the 'partially zero' case.
     return nullptr;

Added: llvm/trunk/test/Transforms/InstCombine/constant-fold-shifts.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/constant-fold-shifts.ll?rev=358192&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/constant-fold-shifts.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/constant-fold-shifts.ll Thu Apr 11 09:39:31 2019
@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+ at A = external constant i32
+
+; OSS-Fuzz #14169
+; https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14169
+define void @ossfuzz_14169_test1(i32* %a0) {
+; CHECK-LABEL: @ossfuzz_14169_test1(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    ret void
+;
+bb:
+  %B = ptrtoint i32* @A to i64
+  %C = icmp sge i64 %B, 0
+  %X = select i1 %C, i712 0, i712 1
+  %B9 = lshr i712 %X, 146783911423364576743092537299333564210980159306769991919205685720763064069663027716481187399048043939495936
+  %G5 = getelementptr i64, i64* undef, i712 %B9
+  store i64* %G5, i64** undef
+  ret void
+}
+
+define void @ossfuzz_14169_test2(i32* %a0) {
+; CHECK-LABEL: @ossfuzz_14169_test2(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    ret void
+;
+bb:
+  %B = ptrtoint i32* @A to i64
+  %C = icmp sge i64 %B, 0
+  %X = select i1 %C, i712 0, i712 1
+  %B9 = shl i712 %X, 146783911423364576743092537299333564210980159306769991919205685720763064069663027716481187399048043939495936
+  %G5 = getelementptr i64, i64* undef, i712 %B9
+  store i64* %G5, i64** undef
+  ret void
+}