Recommit "[MachineVerifier] Improve verification of live-in lists."

MachineVerifier::visitMachineFunctionAfter() is extended to check the
live-through case for live-in lists. This is only done for registers without
aliases and that are neither allocatable or reserved, such as the SystemZ::CC
register.

The MachineVerifier earlier only catched the case of a live-in use without an
entry in the live-in list (as "using an undefined physical register").

A comment in LivePhysRegs.h has been added stating a guarantee that
addLiveOuts() can be trusted for a full register both before and after
register allocation.

Review: Quentin Colombet

Differential Revision: https://reviews.llvm.org/D68267

3 files changed, 125 insertions, 0 deletions

diff --git a/llvm/test/MachineVerifier/live-ins-01.mir b/llvm/test/MachineVerifier/live-ins-01.mir
new file mode 100644
index 00000000000..51c05dacf05
--- /dev/null
+++ b/llvm/test/MachineVerifier/live-ins-01.mir
@@ -0,0 +1,57 @@
+# RUN: not llc -o - %s -mtriple=s390x-linux-gnu -mcpu=z14 -run-pass none 2>&1 | FileCheck %s
+# REQUIRES: systemz-registered-target
+
+# Test that a the machine verifier reports an error when a register in
+# liveins is not liveout from predecessor.
+
+---
+name:            f1
+tracksRegLiveness: true
+machineFunctionInfo: {}
+body:             |
+  bb.0:
+    liveins: $r2l, $r3l
+  
+    %1:gr32bit = COPY $r3l
+    %0:gr32bit = COPY $r2l
+    CHIMux %0, 0, implicit-def $cc
+
+  bb.1:
+    liveins: $cc
+
+  bb.2:
+    liveins: $cc
+
+    %2:grx32bit = LOCRMux %1, %0, 14, 8, implicit $cc
+    $r2l = COPY %2
+    Return implicit $r2l
+...
+
+# CHECK: *** Bad machine code: Live in register not found to be live out from predecessor. ***
+# CHECK:- function:    f2
+# CHECK:- basic block: %bb.2
+# CHECK:CC not found to be live out from %bb.1
+---
+name:            f2
+tracksRegLiveness: true
+machineFunctionInfo: {}
+body:             |
+  bb.0:
+    liveins: $r2l, $r3l
+  
+    %1:gr32bit = COPY $r3l
+    %0:gr32bit = COPY $r2l
+    CHIMux %0, 0, implicit-def $cc
+
+  bb.1:
+    liveins: $cc
+    KILL killed $cc
+
+  bb.2:
+    liveins: $cc
+
+    %2:grx32bit = LOCRMux %1, %0, 14, 8, implicit $cc
+    $r2l = COPY %2
+    Return implicit $r2l
+
+...
diff --git a/llvm/test/MachineVerifier/live-ins-02.mir b/llvm/test/MachineVerifier/live-ins-02.mir
new file mode 100644
index 00000000000..d76325cdd10
--- /dev/null
+++ b/llvm/test/MachineVerifier/live-ins-02.mir
@@ -0,0 +1,32 @@
+# RUN: not llc -o - %s -mtriple=s390x-linux-gnu -mcpu=z14 -run-pass none 2>&1 | FileCheck %s
+# REQUIRES: systemz-registered-target
+
+# Test that a the machine verifier reports an error when a register in
+# liveins is not liveout from predecessor.
+
+---
+name:            f1
+tracksRegLiveness: true
+machineFunctionInfo: {}
+body:             |
+  bb.0:
+    liveins: $r2l, $r3l
+  
+    %1:gr32bit = COPY $r3l
+    %0:gr32bit = COPY $r2l
+    CHIMux %0, 0, implicit-def $cc
+
+  bb.1:
+
+  bb.2:
+    liveins: $cc
+
+    %2:grx32bit = LOCRMux %1, %0, 14, 8, implicit $cc
+    $r2l = COPY %2
+    Return implicit $r2l
+...
+
+# CHECK: *** Bad machine code: Live in register not found to be live out from predecessor. ***
+# CHECK:- function:    f1
+# CHECK:- basic block: %bb.2
+# CHECK:CC not found to be live out from %bb.1
diff --git a/llvm/test/MachineVerifier/live-ins-03.mir b/llvm/test/MachineVerifier/live-ins-03.mir
new file mode 100644
index 00000000000..b5345ccdc3b
--- /dev/null
+++ b/llvm/test/MachineVerifier/live-ins-03.mir
@@ -0,0 +1,36 @@
+# RUN: not llc -o - %s -mtriple=s390x-linux-gnu -mcpu=z14 -run-pass none 2>&1 | FileCheck %s
+# REQUIRES: systemz-registered-target
+
+# Test that a the machine verifier reports an error when a register in
+# liveins is not liveout from predecessor.
+
+---
+name:            f1
+tracksRegLiveness: true
+machineFunctionInfo: {}
+body:             |
+  bb.0:
+    liveins: $r2l, $r3l
+  
+    %1:gr32bit = COPY $r3l
+    %0:gr32bit = COPY $r2l
+    CHIMux %0, 0, implicit-def $cc
+
+  bb.1:
+    liveins: $cc
+    BRC 14, 8, %bb.3, implicit $cc
+
+  bb.2:
+
+  bb.3:
+    liveins: $cc
+
+    %2:grx32bit = LOCRMux %1, %0, 14, 8, implicit $cc
+    $r2l = COPY %2
+    Return implicit $r2l
+...
+
+# CHECK: *** Bad machine code: Live in register not found to be live out from predecessor. ***
+# CHECK:- function:    f1
+# CHECK:- basic block: %bb.3
+# CHECK:CC not found to be live out from %bb.2