[Flang] Restrict emit-asm-from-mlir.mlir to be ran on specific targets using 'target=...'

[amyk]

Summary

This patch aims to restrict the emit-asm-from-mlir.mlir test to the targets that the test
cases expect using the 'target=...' LIT expression.

rG9067de2a43145411eff8b7782a404c5834249717 has previously attempted to
resolve the LIT failure on the ppc64le-flang-rhel-clang buildbot coming from the
emit-asm-from-mlir.mlir test by restricting the test case for AArch64, x86 and ARM
(as long as these targets are built). The original solution of adding "*-registered-target"
works on ppc64le-flang-rhel-clang because this bot only builds PowerPC in
LLVM_TARGETS_TO_BUILD.

When we build all targets and also build the flang project, this test case will fail because
despite being on PowerPC, we are still building the AArch64, x86 and ARM targets which
will cause this test to run. These targets expect the ret instruction to be produced in this
test case, while PowerPC produces a blr instead.

[probinson]

The comment suggests that it wants a (default) target that has particular characteristics, so updating REQUIRES to match that intent seems like a better approach.

flang/test/Driver/emit-asm-from-mlir.mlir

1–2

// REQUIRES: target=aarch64{{.*}} || target=x86{{.*}} || target=arm{{.*}}

[amyk]

flang/test/Driver/emit-asm-from-mlir.mlir

1–2

Good point. I will adjust this REQUIRES line instead.

[amyk]

Address review comment to update the REQUIRES line instead.

[probinson]

LGTM

flang/test/Driver/emit-asm-from-mlir.mlir

-// REQUIRES: aarch64-registered-target || x86-registered-target || arm-registered-target
+// REQUIRES: target=aarch64{{.*}} || target=x86{{.*}} || target=arm{{.*}}
 // Above restricts the test to those architectures that match "ret" to return
 // from a function.
 // Verify that the driver can consume MLIR/FIR files.
 
 // RUN: %flang_fc1 -S %s -o - | FileCheck %s
 
 // CHECK-LABEL: foo:
 // CHECK: ret
 func.func @foo() {
   return
 }