[PATCH] D120596: [clang][CGStmt] fix crash on invalid asm statement

[Tong Zhang via Phabricator via cfe-commits]

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Clang is crashing on the following statement

  char var[9];
  __asm__ ("" : "=r" (var) : "0" (var));

This is similar to existing test: crbug_999160_regtest

The issue happens when EmitAsmStmt is trying to convert input to match
output type length. However, that is not guaranteed to be successful all the
time and if the statement itself is invalid like having an array type in
the example, we should give a regular error message here instead of
using assert().


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D120596

Files:
  clang/lib/CodeGen/CGStmt.cpp
  clang/test/CodeGen/X86/x86_64-PR42672.c


Index: clang/test/CodeGen/X86/x86_64-PR42672.c
===================================================================
--- clang/test/CodeGen/X86/x86_64-PR42672.c
+++ clang/test/CodeGen/X86/x86_64-PR42672.c
@@ -5,6 +5,7 @@
 // RUN: %clang_cc1 -triple=x86_64-unknown-linux-gnu -DPOSSIBLE_X -emit-llvm %s -o - 2>&1 | FileCheck %s --check-prefix=CHECK-X
 // RUN: not %clang_cc1 -triple=x86_64-unknown-linux-gnu -DIMPOSSIBLE_X -emit-llvm %s -o - 2>&1 | FileCheck %s --check-prefix=CHECK-IMPOSSIBLE_X
 // RUN: not %clang_cc1 -triple=x86_64-unknown-linux-gnu -DIMPOSSIBLE_9BYTES -emit-llvm %s -o - 2>&1 | FileCheck %s --check-prefix=CHECK-IMPOSSIBLE_9BYTES
+// RUN: not %clang_cc1 -triple=x86_64-unknown-linux-gnu -DIMPOSSIBLE_9BYTES_V2 -emit-llvm %s -o - 2>&1 | FileCheck %s --check-prefix=CHECK-IMPOSSIBLE_9BYTES_V2

 // Make sure Clang doesn't treat |lockval| as asm input.
 void _raw_spin_lock(void) {
@@ -115,3 +116,12 @@
 }

 // CHECK-IMPOSSIBLE_9BYTES: impossible constraint in asm: can't store value into a register
+
+void crbug_999160_regtest_v2(void) {
+#ifdef IMPOSSIBLE_9BYTES_V2
+  char buf[9];
+  asm(""
+      : "=r"(buf) : "0"(buf));
+#endif
+}
+// CHECK-IMPOSSIBLE_9BYTES_V2: impossible constraint in asm: can't store value into a register
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -2513,10 +2513,8 @@
           Arg = Builder.CreateZExt(Arg, OutputTy);
         else if (isa<llvm::PointerType>(OutputTy))
           Arg = Builder.CreateZExt(Arg, IntPtrTy);
-        else {
-          assert(OutputTy->isFloatingPointTy() && "Unexpected output type");
+        else if (OutputTy->isFloatingPointTy())
           Arg = Builder.CreateFPExt(Arg, OutputTy);
-        }
       }
       // Deal with the tied operands' constraint code in adjustInlineAsmType.
       ReplaceConstraint = OutputConstraints[Output];


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