[clang] f76d3b8 - [clang][CGStmt] fix crash on invalid asm statement

[Fangrui Song via cfe-commits]

Author: Tong Zhang
Date: 2022-03-02T11:18:55-08:00
New Revision: f76d3b800f7341882ea93db47cc8f28d94e74f1c

URL: https://github.com/llvm/llvm-project/commit/f76d3b800f7341882ea93db47cc8f28d94e74f1c
DIFF: https://github.com/llvm/llvm-project/commit/f76d3b800f7341882ea93db47cc8f28d94e74f1c.diff

LOG: [clang][CGStmt] fix crash on invalid asm statement

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().

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D120596

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 011909a5834b8..01ccc71463069 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -2518,10 +2518,8 @@ void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
           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];

diff  --git a/clang/test/CodeGen/X86/x86_64-PR42672.c b/clang/test/CodeGen/X86/x86_64-PR42672.c
index 2e8ec15b58525..6eea20a1e3f63 100644
--- a/clang/test/CodeGen/X86/x86_64-PR42672.c
+++ b/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 +116,11 @@ void crbug_999160_regtest(void) {
 }
 
 // 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