Implement @llvm.is.constant() intrinsic handling and add a test for it.

2 files changed, 51 insertions, 0 deletions

diff --git a/lib/Module/IntrinsicCleaner.cpp b/lib/Module/IntrinsicCleaner.cpp
index 2c86d56d..f59192c1 100644
--- a/lib/Module/IntrinsicCleaner.cpp
+++ b/lib/Module/IntrinsicCleaner.cpp
@@ -11,6 +11,7 @@
 
 #include "klee/Config/Version.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
@@ -324,6 +325,17 @@ bool IntrinsicCleanerPass::runOnBasicBlock(BasicBlock &b, Module &M) {
         dirty = true;
         break;
       }
+#if LLVM_VERSION_CODE >= LLVM_VERSION(8, 0)
+      case Intrinsic::is_constant: {
+        if(auto* constant = llvm::ConstantFoldInstruction(ii, ii->getModule()->getDataLayout()))
+          ii->replaceAllUsesWith(constant);
+        else
+          ii->replaceAllUsesWith(ConstantInt::getFalse(ii->getType()));
+        ii->eraseFromParent();
+        dirty = true;
+        break;
+      }
+#endif
       default:
         IL->LowerIntrinsicCall(ii);
         dirty = true;
diff --git a/test/Intrinsics/IsConstant.ll b/test/Intrinsics/IsConstant.ll
new file mode 100644
index 00000000..b196d933
--- /dev/null
+++ b/test/Intrinsics/IsConstant.ll
@@ -0,0 +1,39 @@
+; REQUIRES: geq-llvm-8.0
+; RUN: %llvmas %s -o=%t.bc
+; RUN: rm -rf %t.klee-out
+; RUN: %klee -exit-on-error --output-dir=%t.klee-out --optimize=false %t.bc
+
+declare i1 @llvm.is.constant.i32(i32)
+
+declare i32 @klee_is_symbolic(i32)
+declare void @klee_abort(i8*)
+
+define i1 @check1() {
+  %r = call i1 @llvm.is.constant.i32(i32 123)
+
+  ret i1 %r
+}
+
+define i1 @check2() {
+  %x = call i32 @klee_is_symbolic(i32 0)
+
+  %r = call i1 @llvm.is.constant.i32(i32 %x)
+
+  %notR = xor i1 %r, 1
+
+  ret i1 %notR
+}
+
+define i32 @main() {
+  %r1 = call i1 @check1()
+  %r2 = call i1 @check2()
+
+  br i1 %r1, label %next, label %exitFalse
+next:
+  br i1 %r2, label %exitTrue, label %exitFalse
+exitFalse:
+  call void @klee_abort(i8* null)
+  ret i32 1
+exitTrue:
+  ret i32 0
+}