[llvm] 69f1442 - [LLVM] BasicTTIImpl allow unknown type during legality checking (#89848)

[via llvm-commits]

Author: Billy Zhu
Date: 2024-05-03T07:30:36-07:00
New Revision: 69f1442302250a23fb981fb4d61159d50551f617

URL: https://github.com/llvm/llvm-project/commit/69f1442302250a23fb981fb4d61159d50551f617
DIFF: https://github.com/llvm/llvm-project/commit/69f1442302250a23fb981fb4d61159d50551f617.diff

LOG: [LLVM] BasicTTIImpl allow unknown type during legality checking (#89848)

Make BasicTTIImplBase's `isTypeLegal` check handle unknown types.
Current behavior is aborting.

Motivated by a use case in SimplifyCFG, where `isTypeLegal` is called on
a struct type and dies, when it could be treated as illegal and skipped.
In general it could make sense for unknown types to be allowed, and by
default just considered not legal, but the behavior can of course be
overriden.

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/BasicTTIImpl.h
    llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/BasicTTIImpl.h b/llvm/include/llvm/CodeGen/BasicTTIImpl.h
index 92b51438b4cb3c..c6e90e57e46edb 100644
--- a/llvm/include/llvm/CodeGen/BasicTTIImpl.h
+++ b/llvm/include/llvm/CodeGen/BasicTTIImpl.h
@@ -426,7 +426,7 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
   bool useAA() const { return getST()->useAA(); }
 
   bool isTypeLegal(Type *Ty) {
-    EVT VT = getTLI()->getValueType(DL, Ty);
+    EVT VT = getTLI()->getValueType(DL, Ty, /*AllowUnknown=*/true);
     return getTLI()->isTypeLegal(VT);
   }
 

diff  --git a/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
index 3873f0c0ae0bbd..9d6502072c16bc 100644
--- a/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
+++ b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
@@ -2068,3 +2068,37 @@ cond.end:                                         ; preds = %entry, %cond.false
   %conv = sext i3 %cond to i8
   ret i8 %conv
 }
+
+; Don't create a table with an unknown type
+define { i8, i8 } @test_unknown_result_type(i8 %n) {
+; CHECK-LABEL: @test_unknown_result_type(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i8 [[N:%.*]], label [[SW_DEFAULT:%.*]] [
+; CHECK-NEXT:      i8 0, label [[RETURN:%.*]]
+; CHECK-NEXT:      i8 1, label [[RETURN]]
+; CHECK-NEXT:      i8 2, label [[RETURN]]
+; CHECK-NEXT:    ]
+; CHECK:       sw.default:
+; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { i8, i8 } undef, i8 0, 0
+; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { i8, i8 } [[TMP0]], i8 1, 1
+; CHECK-NEXT:    br label [[RETURN]]
+; CHECK:       return:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi { i8, i8 } [ undef, [[ENTRY:%.*]] ], [ undef, [[ENTRY]] ], [ undef, [[ENTRY]] ], [ [[TMP1]], [[SW_DEFAULT]] ]
+; CHECK-NEXT:    ret { i8, i8 } [[RETVAL_0]]
+;
+entry:
+  switch i8 %n, label %sw.default [
+  i8 0, label %return
+  i8 1, label %return
+  i8 2, label %return
+  ]
+
+sw.default:                                       ; preds = %entry
+  %0 = insertvalue { i8, i8 } undef, i8 0, 0
+  %1 = insertvalue { i8, i8 } %0, i8 1, 1
+  br label %return
+
+return:                                           ; preds = %sw.default, %entry, %entry, %entry
+  %retval.0 = phi { i8, i8 } [ undef, %entry ], [ undef, %entry ], [ undef, %entry ], [ %1, %sw.default ]
+  ret { i8, i8 } %retval.0
+}