[GlobalIsel] Fix fallback if stack protector isn't supported.

When GlobalISel fails, we need to report the error, and we need to set
the FailedISel property.  We skipped those steps if stack protector
insertion failed, which led to a very strange miscompile.

Differential Revision: https://reviews.llvm.org/D125584

(cherry picked from commit 96c2a0c)

Author: efriedma-quic

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -3469,8 +3469,13 @@ bool IRTranslator::runOnMachineFunction(MachineFunction &CurMF) {
         return false;
       }
 
-      if (!finalizeBasicBlock(*BB, MBB))
+      if (!finalizeBasicBlock(*BB, MBB)) {
+        OptimizationRemarkMissed R("gisel-irtranslator", "GISelFailure",
+                                   BB->getTerminator()->getDebugLoc(), BB);
+        R << "unable to translate basic block";
+        reportTranslationError(*MF, *TPC, *ORE, R);
         return false;
+      }
     }
 #ifndef NDEBUG
     WrapperObserver.removeObserver(&Verifier);

llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-stack-protector-windows.ll

@@ -0,0 +1,38 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-pc-windows-msvc %s -o - -global-isel -global-isel-abort=0 | FileCheck %s
+
+; Make sure we correctly fall back to SelectionDAG isel for unsupported stack protectors.
+
+define void @caller() sspreq {
+; CHECK-LABEL: caller:
+; CHECK:       .seh_proc caller
+; CHECK-NEXT:  // %bb.0: // %entry
+; CHECK-NEXT:    sub sp, sp, #32
+; CHECK-NEXT:    .seh_stackalloc 32
+; CHECK-NEXT:    str x30, [sp, #16] // 8-byte Folded Spill
+; CHECK-NEXT:    .seh_save_reg x30, 16
+; CHECK-NEXT:    .seh_endprologue
+; CHECK-NEXT:    adrp x8, __security_cookie
+; CHECK-NEXT:    add x0, sp, #4
+; CHECK-NEXT:    ldr x8, [x8, :lo12:__security_cookie]
+; CHECK-NEXT:    str x8, [sp, #8]
+; CHECK-NEXT:    bl callee
+; CHECK-NEXT:    ldr x0, [sp, #8]
+; CHECK-NEXT:    bl __security_check_cookie
+; CHECK-NEXT:    .seh_startepilogue
+; CHECK-NEXT:    ldr x30, [sp, #16] // 8-byte Folded Reload
+; CHECK-NEXT:    .seh_save_reg x30, 16
+; CHECK-NEXT:    add sp, sp, #32
+; CHECK-NEXT:    .seh_stackalloc 32
+; CHECK-NEXT:    .seh_endepilogue
+; CHECK-NEXT:    ret
+; CHECK-NEXT:    .seh_endfunclet
+; CHECK-NEXT:    .seh_endproc
+entry:
+  %x = alloca i32, align 4
+  %0 = bitcast i32* %x to i8*
+  call void @callee(i32* nonnull %x)
+  ret void
+}
+
+declare void @callee(i32*)