[CodeGen] Handle mixed-width ops in mixed-sign mul-with-overflow lowering

The special lowering for __builtin_mul_overflow introduced in r320902
fixed an ICE seen when passing mixed-sign operands to the builtin.

This patch extends the special lowering to cover mixed-width, mixed-sign
operands. In a few common scenarios, calls to muloti4 will no longer be
emitted.

This should address the latest comments in PR34920 and work around the
link failure seen in:

  https://bugzilla.redhat.com/show_bug.cgi?id=1657544

Testing:
- check-clang
- A/B output comparison with: https://gist.github.com/vedantk/3eb9c88f82e5c32f2e590555b4af5081

Differential Revision: https://reviews.llvm.org/D55843

llvm-svn: 349542

1 files changed, 21 insertions, 0 deletions

diff --git a/clang/test/CodeGen/builtins-overflow.c b/clang/test/CodeGen/builtins-overflow.c
index 57f90eb66a5..79a3186b745 100644
--- a/clang/test/CodeGen/builtins-overflow.c
+++ b/clang/test/CodeGen/builtins-overflow.c
@@ -339,6 +339,27 @@ long long test_smulll_overflow(long long x, long long y) {
   return result;
 }
 
+int test_mixed_sign_mul_overflow_sext_signed_op(int x, unsigned long long y) {
+// CHECK: @test_mixed_sign_mul_overflow_sext_signed_op
+// CHECK: [[SignedOp:%.*]] = sext i32 %0 to i64
+// CHECK: [[IsNeg:%.*]] = icmp slt i64 [[SignedOp]], 0
+  int result;
+  if (__builtin_mul_overflow(x, y, &result))
+    return LongErrorCode;
+  return result;
+}
+
+int test_mixed_sign_mul_overflow_zext_unsigned_op(long long x, unsigned y) {
+// CHECK: @test_mixed_sign_mul_overflow_zext_unsigned_op
+// CHECK: [[UnsignedOp:%.*]] = zext i32 %1 to i64
+// CHECK: [[IsNeg:%.*]] = icmp slt i64 %0, 0
+// CHECK: @llvm.umul.with.overflow.i64({{.*}}, i64 [[UnsignedOp]])
+  int result;
+  if (__builtin_mul_overflow(x, y, &result))
+    return LongErrorCode;
+  return result;
+}
+
 int test_mixed_sign_mull_overflow(int x, unsigned y) {
 // CHECK: @test_mixed_sign_mull_overflow
 // CHECK:       [[IsNeg:%.*]] = icmp slt i32 [[Op1:%.*]], 0