[SimplifyLibCalls] Recognize and simplify f[min/max]imumnum

[valadaptive]

Unlike fmin and fmax, these are deterministic with regards to signed
zero.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: None (valadaptive)

Changes

Unlike fmin and fmax, these are deterministic with regards to signed
zero.

---

Full diff: https://github.com/llvm/llvm-project/pull/170699.diff

2 Files Affected:

• (modified) llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h (+1)
• (modified) llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp (+31)

diff --git a/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h b/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
index 4e7c97194cc59..64d2512308935 100644
--- a/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
+++ b/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
@@ -205,6 +205,7 @@ class LibCallSimplifier {
   Value *replacePowWithSqrt(CallInst *Pow, IRBuilderBase &B);
   Value *optimizeExp2(CallInst *CI, IRBuilderBase &B);
   Value *optimizeFMinFMax(CallInst *CI, IRBuilderBase &B);
+  Value *optimizeFMinimumnumFMaximumnum(CallInst *CI, IRBuilderBase &B);
   Value *optimizeLog(CallInst *CI, IRBuilderBase &B);
   Value *optimizeSqrt(CallInst *CI, IRBuilderBase &B);
   Value *optimizeFMod(CallInst *CI, IRBuilderBase &B);
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index d1548694baa27..20d9b03bd87c8 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2543,6 +2543,30 @@ Value *LibCallSimplifier::optimizeFMinFMax(CallInst *CI, IRBuilderBase &B) {
                                                 CI->getArgOperand(1), FMF));
 }
 
+Value *LibCallSimplifier::optimizeFMinimumnumFMaximumnum(CallInst *CI,
+                                                         IRBuilderBase &B) {
+  Module *M = CI->getModule();
+
+  // If we can shrink the call to a float function rather than a double
+  // function, do that first.
+  Function *Callee = CI->getCalledFunction();
+  StringRef Name = Callee->getName();
+  if ((Name == "fminimum_num" || Name == "fmaximum_num") &&
+      hasFloatVersion(M, Name))
+    if (Value *Ret = optimizeBinaryDoubleFP(CI, B, TLI))
+      return Ret;
+
+  // The new fminimum_num/fmaximum_num functions, unlike fmin/fmax, *are*
+  // sensitive to the sigh of zero, so we don't change the fast-math flags like
+  // we did for those.
+
+  Intrinsic::ID IID = Callee->getName().starts_with("fminimum_num")
+                          ? Intrinsic::minimumnum
+                          : Intrinsic::maximumnum;
+  return copyFlags(*CI, B.CreateBinaryIntrinsic(IID, CI->getArgOperand(0),
+                                                CI->getArgOperand(1), CI));
+}
+
 Value *LibCallSimplifier::optimizeLog(CallInst *Log, IRBuilderBase &B) {
   Function *LogFn = Log->getCalledFunction();
   StringRef LogNm = LogFn->getName();
@@ -4123,6 +4147,13 @@ Value *LibCallSimplifier::optimizeFloatingPointLibCall(CallInst *CI,
   case LibFunc_fmax:
   case LibFunc_fmaxl:
     return optimizeFMinFMax(CI, Builder);
+  case LibFunc_fminimum_numf:
+  case LibFunc_fminimum_num:
+  case LibFunc_fminimum_numl:
+  case LibFunc_fmaximum_numf:
+  case LibFunc_fmaximum_num:
+  case LibFunc_fmaximum_numl:
+    return optimizeFMinimumnumFMaximumnum(CI, Builder);
   case LibFunc_cabs:
   case LibFunc_cabsf:
   case LibFunc_cabsl:

[dtcxzyw]

Missing tests

[valadaptive]

I added tests in #170695; I've pulled those in now

[dtcxzyw]

LGTM

[arsenm]

Why does this need the string compare? TargetLibraryInfo should have already parsed this into an enum LibFunc in the caller? Pass that down?

[valadaptive]

I mostly just adapted this from optimizeFMinFMax above. We could indeed pass in the LibFunc to both functions, although we still need to get the function name to pass into hasFloatVersion.

[arsenm]

Should do that then? I would like to eliminate all string-based libcall logic throughout llvm