[FPEnv] [Clang] Enable constrained FP support for PowerPC

[qiucf]

Summary

D80952 introduced HasStrictFP to disable generating constrained FP operations for platforms lacking support. Since work for enabling constrained FP on PowerPC is almost done, we'd like to enable it.

[kpn]

Over in D80952 there was a comment from @steven.zhang: "Agree that we can turn on it later when it is done." But your comment here is that it is "almost done".

Is it fair to say that the PowerPC work is at _parity_ with X86 and SystemZ? I think that's a better cutover point than "done".

[qiucf]

In D87223#2261086, @kpn wrote:

Over in D80952 there was a comment from @steven.zhang: "Agree that we can turn on it later when it is done." But your comment here is that it is "almost done".

Is it fair to say that the PowerPC work is at _parity_ with X86 and SystemZ? I think that's a better cutover point than "done".

Yes, we've disabled the FP mutation in rG6afb2791. vector-constrained-fp-intrinsics.ll is also aligned with X86 & SystemZ.

[kpn]

In D87223#2265348, @qiucf wrote:

In D87223#2261086, @kpn wrote:

Over in D80952 there was a comment from @steven.zhang: "Agree that we can turn on it later when it is done." But your comment here is that it is "almost done".

Is it fair to say that the PowerPC work is at _parity_ with X86 and SystemZ? I think that's a better cutover point than "done".

Yes, we've disabled the FP mutation in rG6afb2791. vector-constrained-fp-intrinsics.ll is also aligned with X86 & SystemZ.

Ok, LGTM. Please wait a few days in case anyone else has any comments.

[steven.zhang]

LGTM as far as you have verified the bmk, bootstrap with strict-fp enabled.

clang/lib/Basic/Targets/PPC.h

 
 public:
   PPCTargetInfo(const llvm::Triple &Triple, const TargetOptions &)
       : TargetInfo(Triple) {
     SuitableAlign = 128;
     SimdDefaultAlign = 128;
     LongDoubleWidth = LongDoubleAlign = 128;
     LongDoubleFormat = &llvm::APFloat::PPCDoubleDouble();
+    HasStrictFP = true;
   }
 
   // Set the language option for altivec based on our value.
   void adjust(LangOptions &Opts) override;
 
   // Note: GCC recognizes the following additional cpus:
   //  401, 403, 405, 405fp, 440fp, 464, 464fp, 476, 476fp, 505, 740, 801,
   //  821, 823, 8540, e300c2, e300c3, e500mc64, e6500, 860, cell, titan, rs64.

clang/test/CodeGen/builtins-ppc-fpconstrained.c

 // REQUIRES: powerpc-registered-target
 // RUN: %clang_cc1 -triple powerpc64le-gnu-linux -target-feature +vsx \
 // RUN: -emit-llvm %s -o - | FileCheck --check-prefix=CHECK-UNCONSTRAINED %s
 // RUN: %clang_cc1 -triple powerpc64le-gnu-linux -target-feature +vsx \
-// RUN: -fexperimental-strict-floating-point \
 // RUN:  -ffp-exception-behavior=strict -emit-llvm %s -o - | FileCheck \
 // RUN: --check-prefix=CHECK-CONSTRAINED -vv %s
 // RUN: %clang_cc1 -triple powerpc64le-gnu-linux -target-feature +vsx \
 // RUN: -fallow-half-arguments-and-returns -S -o - %s | \
 // RUN: FileCheck --check-prefix=CHECK-ASM --check-prefix=NOT-FIXME-CHECK  %s
 // RUN: %clang_cc1 -triple powerpc64le-gnu-linux -target-feature +vsx \
-// RUN: -fexperimental-strict-floating-point \
 // RUN: -fallow-half-arguments-and-returns -S -ffp-exception-behavior=strict \
 // RUN: -o - %s | FileCheck --check-prefix=CHECK-ASM \
 // RUN: --check-prefix=FIXME-CHECK  %s
 
 typedef __attribute__((vector_size(4 * sizeof(float)))) float vec_float;
 typedef __attribute__((vector_size(2 * sizeof(double)))) double vec_double;
 
 volatile vec_double vd;