Clang/MIPS: Add +fp64 if MSA and no explicit -mfp option (llvm#91949)

MSA requires -mfp64. If FP64 is supported by CPU (mips32r2+), and no
-mfp32/-mfpxx is explicitly given, let's add +fp64. Otherwise some cmd
like
   clang --target=mips -mips32r5 -mmsa
will issue LLVM backend ICE.

Author: wzssyqa

clang/lib/Driver/ToolChains/Arch/Mips.cpp

@@ -369,6 +369,9 @@ void mips::getMIPSTargetFeatures(const Driver &D, const llvm::Triple &Triple,
   } else if (mips::isFP64ADefault(Triple, CPUName)) {
     Features.push_back("+fp64");
     Features.push_back("+nooddspreg");
+  } else if (Arg *A = Args.getLastArg(options::OPT_mmsa)) {
+    if (A->getOption().matches(options::OPT_mmsa))
+      Features.push_back("+fp64");
   }
 
   AddTargetFeature(Args, Features, options::OPT_mno_odd_spreg,
@@ -499,6 +502,13 @@ bool mips::shouldUseFPXX(const ArgList &Args, const llvm::Triple &Triple,
                                options::OPT_mdouble_float))
     if (A->getOption().matches(options::OPT_msingle_float))
       UseFPXX = false;
+  // FP64 should be used for MSA.
+  if (Arg *A = Args.getLastArg(options::OPT_mmsa))
+    if (A->getOption().matches(options::OPT_mmsa))
+      UseFPXX = llvm::StringSwitch<bool>(CPUName)
+                    .Cases("mips32r2", "mips32r3", "mips32r5", false)
+                    .Cases("mips64r2", "mips64r3", "mips64r5", false)
+                    .Default(UseFPXX);
 
   return UseFPXX;
 }

clang/test/Driver/mips-as.c

@@ -266,7 +266,7 @@
 // RUN: %clang -target mips-linux-gnu -mno-msa -mmsa -### \
 // RUN:   -no-integrated-as -fno-pic -c %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=MIPS-MSA %s
-// MIPS-MSA: as{{(.exe)?}}" "-march" "mips32r2" "-mabi" "32" "-mno-shared" "-call_nonpic" "-EB" "-mfpxx" "-mmsa"
+// MIPS-MSA: as{{(.exe)?}}" "-march" "mips32r2" "-mabi" "32" "-mno-shared" "-call_nonpic" "-EB" "-mmsa"
 //
 // RUN: %clang -target mips-linux-gnu -mmsa -mno-msa -### \
 // RUN:   -no-integrated-as -fno-pic -c %s 2>&1 \

clang/test/Driver/mips-features.c

@@ -163,6 +163,12 @@
 // RUN:   | FileCheck --check-prefix=CHECK-NOMMSA %s
 // CHECK-NOMMSA: "-target-feature" "-msa"
 //
+// -mmsa
+// RUN: %clang -target mips-linux-gnu -### -c %s \
+// RUN:     -mmsa 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MMSA-MFP64 %s
+// CHECK-MMSA-MFP64: "-target-feature" "+msa" "-target-feature" "+fp64"
+//
 // -mmt
 // RUN: %clang -target mips-linux-gnu -### -c %s \
 // RUN:     -mno-mt -mmt 2>&1 \