Fix implementation of DAGTypeLegalizer::PerformExpensiveChecks

[sepavloff]

Summary

Implementation of DAGTypeLegalizer::PerformExpensiveChecks is out of sync
with the current algorithm of the type legalizer. In particular, it requests
that unprocessed nodes marked as NewNode must not be present in any of the
conversion maps except probably ReplacedValues. It is not true now, abandoned
nodes (they are also marked as NewNode) now may be found in the map
SoftenedFloats as well.

This change fixes several fails when expensive checks are enabled.

[sepavloff]

Added one more case where legalization failed

With current implementation of the legalizer a node may present in both
SoftenedFloats and ReplacedValues. Now this change fixes 9 test fails
observed in builds with expensive checks enabled.

[fhahn]

I don't think we have to make the checks more permissive. I think it is possible to preserve the properties that DAGTypeLegalizer::PerformExpensiveChecks checks. See D29265 for my patch for that. I think we should remove replaced values from SoftenedFloats (and possibly other maps as well).

[RKSimon]

D29265 appears to be trying to achieve the same aim but with a different approach (removing stale entries from SoftenedFloats)

[sepavloff]

Remove changes that relates to intersection of ReplacedValues and SoftenedFloats.

They are covered by D29265.

[sepavloff]

Any feedback?

[sepavloff]

With current ToT (r297001) none of the llvm tests fails due to legalizer, if expensive checks are enabled. So the fix is not needed anymore.

lib/CodeGen/SelectionDAG/LegalizeTypes.cpp

for (unsigned i = 0, e = Node.getNumValues(); i != e; ++i) {
         Mapped |= 128;
       if (PromotedFloats.find(Res) != PromotedFloats.end())
         Mapped |= 256;
 
       if (Node.getNodeId() != Processed) {
         // Since we allow ReplacedValues to map deleted nodes, it may map nodes
         // marked NewNode too, since a deleted node may have been reallocated as
         // another node that has not been seen by the LegalizeTypes machinery.
-        if ((Node.getNodeId() == NewNode && Mapped > 1) ||
+        // Treatment of SoftenedFloats may also create nodes that are abandoned
+        // latter.
+        if ((Node.getNodeId() == NewNode && Mapped > 1 && Mapped != 4) ||
             (Node.getNodeId() != NewNode && Mapped != 0)) {
           dbgs() << "Unprocessed value in a map!";
           Failed = true;
         }
       } else if (isTypeLegal(Res.getValueType()) || IgnoreNodeResults(&Node)) {
         if (Mapped > 1) {
           dbgs() << "Value with legal type was transformed!";
           Failed = true;

test/CodeGen/ARM/fp16.ll

 ; RUN: llc -mtriple=armv7a--none-eabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-HARDFLOAT-EABI %s
 ; RUN: llc -mtriple=armv7a--none-gnueabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-HARDFLOAT-GNU %s
 ; RUN: llc -mtriple=armv7a--none-musleabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-HARDFLOAT-GNU %s
 ; RUN: llc -mtriple=armv8-eabihf < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-ARMV8 %s
-; RUN: llc -mtriple=thumbv7m-eabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-SOFTFLOAT-EABI %s
+; RUN: llc -mtriple=thumbv7m-eabi -enable-legalize-types-checking < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-SOFTFLOAT-EABI %s
 ; RUN: llc -mtriple=thumbv7m-gnueabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-SOFTFLOAT-GNU %s
 ; RUN: llc -mtriple=thumbv7m-musleabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-SOFTFLOAT-GNU %s
 
 ;; +fp16 is special: it has f32->f16 (unlike v7), but not f64->f16 (unlike v8).
 ;; This exposes unsafe-fp-math optimization opportunities; test that.
 ; RUN: llc -mattr=+vfp3,+fp16 < %s |\
 ; RUN:   FileCheck --check-prefix=CHECK --check-prefix=CHECK-FP16 --check-prefix=CHECK-FP16-SAFE %s
 ; RUN: llc -mattr=+vfp3,+fp16 < %s -enable-unsafe-fp-math |\