[PATCH] D72189: [SystemZ] Support -msoft-float

[Ulrich Weigand via Phabricator via llvm-commits]

uweigand added a comment.

In D72189#1850468 <https://reviews.llvm.org/D72189#1850468>, @jonpa wrote:

> > Ah, I see. But note that you're now not supporting "use-soft-float" at all (which I think is fine at this step!), so you should update all tests to no longer use "use-soft-float".
>
> Done. 
>  All llc invocations use -mattr=soft-float instead of relying on the function attributes, as must be done.


Ok, good.

> Addded a new test systemz-float-02.c to check that -msoft-float actually works all the way to assembly output. The type v4si using vector_size() gives a different output compared to gcc, so I guess this is implementation defined?

What's the difference in assembler?    Could this be because you've implemented the VectorABI check the wrong way around?   (If soft-float, then we have *no* VectorABI!)



================
Comment at: clang/lib/Basic/Targets/SystemZ.h:122
     // If we use the vector ABI, vector types are 64-bit aligned.
-    if (HasVector) {
+    if (HasVector || SoftFloat) {
       MaxVectorAlign = 64;
----------------
Eh, I guess that should be "HasVector && !SoftFloat".


================
Comment at: llvm/lib/Target/SystemZ/SystemZISelLowering.cpp:1176
     }
     if (Constraint[1] == 'v') {
       if (VT == MVT::f32)
----------------
This should have "&& Subtarget.hasVector()" here.  Shouldn't that fix the problem with {v}?

If it does not, I agree this can wait for another patch.


================
Comment at: llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp:57
+  if (FS.contains("+soft-float"))
+    VectorABI = true;
+
----------------
No, VectorABI = false then.

Also, should you look for "soft-float" and "-soft-float", just as is done for "vector" above?


================
Comment at: llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp:199
   if (getOptLevel() != CodeGenOpt::None) {
-    addPass(createSystemZTDCPass());
+    if (!((SystemZTargetMachine*) TM)->getSubtargetImpl()->hasSoftFloat())
+      addPass(createSystemZTDCPass());
----------------
This can be just getTM<SystemZTargetMachine>() instead of the manual cast.


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