[PATCH] D46455: [MachineVerifier][GlobalISel] Checking that generic instrs have LLTs on all vregs

[Roman Tereshin via Phabricator via llvm-commits]

rtereshin created this revision.
rtereshin added reviewers: t.p.northover, bogner, qcolombet, ab.
Herald added subscribers: llvm-commits, kristof.beyls, rovka.

Every generic machine instruction must have generic virtual registers
only, that is, have a low-level type attached to each operand.

Previously MachineVerifier would catch a type missing on an operand
only if the previous operand for the the same type index exists and
have a type attached to it and it will report it as a type mismatch.
This is incosistent behaviour and a misleading error message.

This commit makes sure MachineVerifier explicitly checks that the
types are there for every operand and if not provides a
straightforward error message.


Repository:
  rL LLVM

https://reviews.llvm.org/D46455

Files:
  lib/CodeGen/MachineInstr.cpp
  lib/CodeGen/MachineVerifier.cpp
  test/CodeGen/X86/verifier-generic-types-1.mir
  test/CodeGen/X86/verifier-generic-types-2.mir


Index: test/CodeGen/X86/verifier-generic-types-2.mir
===================================================================
--- test/CodeGen/X86/verifier-generic-types-2.mir
+++ test/CodeGen/X86/verifier-generic-types-2.mir
@@ -1,9 +1,16 @@
 # RUN: not llc -o - %s -mtriple=x86_64-- -verify-machineinstrs -run-pass=none 2>&1 | FileCheck %s
 
-# CHECK: Bad machine code: type mismatch in generic instruction
+# CHECK: Bad machine code: Generic instruction is missing a virtual register type
 # CHECK-NEXT: - function:    first_type_of_a_type_index_missing_and_a_mismatch
 # CHECK-NEXT: - basic block: %bb.0
-# CHECK-NEXT: - instruction: %2:gr64 = G_ADD %0:_, %1:_
+# CHECK-NEXT: - instruction: %2:gr64 = G_ADD %0:_(s64), %1:_
+# CHECK-NEXT: - operand 0:   %2:gr64
+
+# CHECK: Bad machine code: Type mismatch in generic instruction
+# CHECK-NEXT: - function:    first_type_of_a_type_index_missing_and_a_mismatch
+# CHECK-NEXT: - basic block: %bb.0
+# CHECK-NEXT: - instruction: %2:gr64 = G_ADD %0:_(s64), %1:_
+# CHECK-NEXT: - operand 2:   %1:_(s32)
 
 ---
 name:              first_type_of_a_type_index_missing_and_a_mismatch
Index: test/CodeGen/X86/verifier-generic-types-1.mir
===================================================================
--- test/CodeGen/X86/verifier-generic-types-1.mir
+++ test/CodeGen/X86/verifier-generic-types-1.mir
@@ -1,5 +1,4 @@
 # RUN: not llc -o - %s -mtriple=x86_64-- -verify-machineinstrs -run-pass=none 2>&1 | FileCheck %s
-# XFAIL: *
 
 # CHECK-NOT: Type mismatch
 
Index: lib/CodeGen/MachineVerifier.cpp
===================================================================
--- lib/CodeGen/MachineVerifier.cpp
+++ lib/CodeGen/MachineVerifier.cpp
@@ -929,9 +929,19 @@
 
       const MachineOperand *MO = &MI->getOperand(I);
       LLT OpTy = MRI->getType(MO->getReg());
-      if (Types[TypeIdx].isValid() && Types[TypeIdx] != OpTy)
-        report("type mismatch in generic instruction", MI);
-      Types[TypeIdx] = OpTy;
+      // Don't report a type mismatch if there is no actual mismatch, only a
+      // type missing, to reduce noise:
+      if (OpTy.isValid()) {
+        // Only the first valid type for a type index will be printed: don't
+        // overwrite it later so it's always clear which type was expected:
+        if (!Types[TypeIdx].isValid())
+          Types[TypeIdx] = OpTy;
+        else if (Types[TypeIdx] != OpTy)
+          report("Type mismatch in generic instruction", MO, I, OpTy);
+      } else {
+        // Generic instructions must have types attached to their operands.
+        report("Generic instruction is missing a virtual register type", MO, I);
+      }
     }
 
     // Generic opcodes must not have physical register operands.
Index: lib/CodeGen/MachineInstr.cpp
===================================================================
--- lib/CodeGen/MachineInstr.cpp
+++ lib/CodeGen/MachineInstr.cpp
@@ -1224,8 +1224,12 @@
   if (PrintedTypes[OpInfo.getGenericTypeIndex()])
     return LLT{};
 
-  PrintedTypes.set(OpInfo.getGenericTypeIndex());
-  return MRI.getType(Op.getReg());
+  LLT TypeToPrint = MRI.getType(Op.getReg());
+  // Don't mark the type index printed if it wasn't actually printed: maybe
+  // another operand with the same type index has an actual type attached:
+  if (TypeToPrint.isValid())
+    PrintedTypes.set(OpInfo.getGenericTypeIndex());
+  return TypeToPrint;
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)


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