[llvm] [ARM] fix "+fp.dp" in multilib selection (PR #67412)

[Dominik Wójt via llvm-commits]

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@@ -366,26 +366,50 @@ StringRef ARM::getArchExtFeature(StringRef ArchExt) {
 }
 
 static ARM::FPUKind findDoublePrecisionFPU(ARM::FPUKind InputFPUKind) {
+  if (InputFPUKind == ARM::FK_INVALID || InputFPUKind == ARM::FK_NONE)
+    return ARM::FK_INVALID;
+
+  const ARM::FPUName &InputFPU = ARM::FPUNames[InputFPUKind];
+
+  if (ARM::isDoublePrecision(InputFPU.Restriction))
+    return InputFPUKind;
+
+  // Otherwise, look for an FPU entry with all the same fields, except
+  // that it supports double precision.
+  for (const ARM::FPUName &CandidateFPU : ARM::FPUNames) {
+    if (CandidateFPU.FPUVer == InputFPU.FPUVer &&
+        CandidateFPU.NeonSupport == InputFPU.NeonSupport &&
+        ARM::has32Regs(CandidateFPU.Restriction) ==
+            ARM::has32Regs(InputFPU.Restriction) &&
+        ARM::isDoublePrecision(CandidateFPU.Restriction)) {
+      return CandidateFPU.ID;
+    }
+  }
+
+  // nothing found
+  return ARM::FK_INVALID;
+}
+
+static ARM::FPUKind findSinglePrecisionFPU(ARM::FPUKind InputFPUKind) {
+  if (InputFPUKind == ARM::FK_INVALID || InputFPUKind == ARM::FK_NONE)
+    return ARM::FK_INVALID;
+
   const ARM::FPUName &InputFPU = ARM::FPUNames[InputFPUKind];
 
   // If the input FPU already supports double-precision, then there
   // isn't any different FPU we can return here.
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domin144 wrote:

Indeed. Thanks for spotting this.

https://github.com/llvm/llvm-project/pull/67412