[CodeGen] "PromoteInteger" f32 to f64 doesn't make sense.

The original f32->f64 promotion logic was refactored into roughly the
currently shape in r37781. However, starting with r132263, the
legalizer has been split into different kinds, and the previous
"Promote" (which did the right thing) was search-and-replace'd into
"PromoteInteger". The divide gradually deepened, with type legalization
("PromoteInteger") being separated from ops legalization
("Promote", which still works for floating point ops).

Fast-forward to today: there's no in-tree target with legal f64 but
illegal f32 (rather: no tests were harmed in the making of this patch).

With such a target, i.e., if you trick the legalizer into going through
the PromoteInteger path for FP, you get the expected brokenness.
For instance, there's no PromoteIntRes_FADD (the name itself sounds
wrong), so we'll just hit some assert in the PromoteInteger path.

Don't pretend we can promote f32 to f64. Instead, always soften.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233464 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TargetLoweringBase.cpp b/lib/CodeGen/TargetLoweringBase.cpp
index 58a6d521855aa04d4036359cc313479d1333781b..2162a513b43d1e4b59e3a4ad9544c10f4de62755 100644 (file)
--- a/lib/CodeGen/TargetLoweringBase.cpp
+++ b/lib/CodeGen/TargetLoweringBase.cpp
@@ -1246,20 +1246,13 @@ void TargetLoweringBase::computeRegisterProperties(
     ValueTypeActions.setTypeAction(MVT::f64, TypeSoftenFloat);
   }
 
-  // Decide how to handle f32. If the target does not have native support for
-  // f32, promote it to f64 if it is legal. Otherwise, expand it to i32.
+  // Decide how to handle f32. If the target does not have native f32 support,
+  // expand it to i32 and we will be generating soft float library calls.
   if (!isTypeLegal(MVT::f32)) {
-    if (isTypeLegal(MVT::f64)) {
-      NumRegistersForVT[MVT::f32] = NumRegistersForVT[MVT::f64];
-      RegisterTypeForVT[MVT::f32] = RegisterTypeForVT[MVT::f64];
-      TransformToType[MVT::f32] = MVT::f64;
-      ValueTypeActions.setTypeAction(MVT::f32, TypePromoteInteger);
-    } else {
-      NumRegistersForVT[MVT::f32] = NumRegistersForVT[MVT::i32];
-      RegisterTypeForVT[MVT::f32] = RegisterTypeForVT[MVT::i32];
-      TransformToType[MVT::f32] = MVT::i32;
-      ValueTypeActions.setTypeAction(MVT::f32, TypeSoftenFloat);
-    }
+    NumRegistersForVT[MVT::f32] = NumRegistersForVT[MVT::i32];
+    RegisterTypeForVT[MVT::f32] = RegisterTypeForVT[MVT::i32];
+    TransformToType[MVT::f32] = MVT::i32;
+    ValueTypeActions.setTypeAction(MVT::f32, TypeSoftenFloat);
   }
 
   if (!isTypeLegal(MVT::f16)) {