[Transforms] Add more cos combinations to SimplifyLibCalls and InstCombine (#79699)

Add cos(fabs(x)) -> cos(x) and cos(copysign(x, y)) -> cos(x).

Author: AZero13

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -2488,11 +2488,13 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
   }
   case Intrinsic::cos:
   case Intrinsic::amdgcn_cos: {
-    Value *X;
+    Value *X, *Sign;
     Value *Src = II->getArgOperand(0);
-    if (match(Src, m_FNeg(m_Value(X))) || match(Src, m_FAbs(m_Value(X)))) {
-      // cos(-x) -> cos(x)
-      // cos(fabs(x)) -> cos(x)
+    if (match(Src, m_FNeg(m_Value(X))) || match(Src, m_FAbs(m_Value(X))) ||
+        match(Src, m_CopySign(m_Value(X), m_Value(Sign)))) {
+      // cos(-x) --> cos(x)
+      // cos(fabs(x)) --> cos(x)
+      // cos(copysign(x, y)) --> cos(x)
       return replaceOperand(*II, 0, X);
     }
     break;

llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

@@ -1933,12 +1933,18 @@ static Value *optimizeTrigReflections(CallInst *Call, LibFunc Func,
     break;
   case LibFunc_cos:
   case LibFunc_cosf:
-  case LibFunc_cosl:
-    // cos(-X) --> cos(X)
-    if (match(Call->getArgOperand(0), m_FNeg(m_Value(X))))
+  case LibFunc_cosl: {
+    // cos(-x) --> cos(x)
+    // cos(fabs(x)) --> cos(x)
+    // cos(copysign(x, y)) --> cos(x)
+    Value *Sign;
+    Value *Src = Call->getArgOperand(0);
+    if (match(Src, m_FNeg(m_Value(X))) || match(Src, m_FAbs(m_Value(X))) ||
+        match(Src, m_CopySign(m_Value(X), m_Value(Sign))))
       return copyFlags(*Call,
                        B.CreateCall(Call->getCalledFunction(), X, "cos"));
     break;
+  }
   default:
     break;
   }

llvm/test/Transforms/InstCombine/cos-1.ll

@@ -17,6 +17,14 @@ declare float @llvm.sin.f32(float)
 declare double @tan(double)
 declare fp128 @tanl(fp128)
 
+declare double @fabs(double)
+declare double @llvm.fabs.f64(double)
+declare float @fabsf(float)
+declare float @llvm.fabs.f32(float)
+
+declare double @llvm.copysign(double, double)
+declare float @llvm.copysign.f32(float, float)
+
 ; cos(-x) -> cos(x);
 
 define double @cos_negated_arg(double %x) {
@@ -100,6 +108,71 @@ define float @cosf_unary_negated_arg_FMF(float %x) {
   ret float %r
 }
 
+; cos(fabs(x)) -> cos(x)
+
+define double @cos_unary_fabs_arg(double %x) {
+; ANY-LABEL: @cos_unary_fabs_arg(
+; ANY-NEXT:    [[COS:%.*]] = call double @cos(double [[X:%.*]])
+; ANY-NEXT:    ret double [[COS]]
+;
+  %fabs = tail call double @llvm.fabs.f64(double %x)
+  %r = call double @cos(double %fabs)
+  ret double %r
+}
+
+define float @cosf_unary_fabs_arg(float %x) {
+; ANY-LABEL: @cosf_unary_fabs_arg(
+; ANY-NEXT:    [[COS:%.*]] = call float @cosf(float [[X:%.*]])
+; ANY-NEXT:    ret float [[COS]]
+;
+  %fabs = tail call float @llvm.fabs.f32(float %x)
+  %r = call float @cosf(float %fabs)
+  ret float %r
+}
+
+define float @cosf_unary_fabs_arg_FMF(float %x) {
+; ANY-LABEL: @cosf_unary_fabs_arg_FMF(
+; ANY-NEXT:    [[COS:%.*]] = call reassoc nnan float @cosf(float [[X:%.*]])
+; ANY-NEXT:    ret float [[COS]]
+;
+  %fabs = tail call float @llvm.fabs.f32(float %x)
+  %r = call nnan reassoc float @cosf(float %fabs)
+  ret float %r
+}
+
+; cos(copysign(x, y)) -> cos(x)
+
+define double @cos_copysign_arg(double %x, double %y) {
+; ANY-LABEL: @cos_copysign_arg(
+; ANY-NEXT:    [[COS:%.*]] = call double @cos(double [[X:%.*]])
+; ANY-NEXT:    ret double [[COS]]
+;
+  %copysign = tail call double @llvm.copysign(double %x, double %y)
+  %r = call double @cos(double %copysign)
+  ret double %r
+}
+
+
+define float @cosf_unary_copysign_arg(float %x) {
+; ANY-LABEL: @cosf_unary_copysign_arg(
+; ANY-NEXT:    [[COS:%.*]] = call float @cosf(float [[X:%.*]])
+; ANY-NEXT:    ret float [[COS]]
+;
+  %copysign = tail call float @llvm.copysign.f32(float %x, float 1.0)
+  %r = call float @cosf(float %copysign)
+  ret float %r
+}
+
+define float @cosf_copysign_arg_FMF(float %x, float %y) {
+; ANY-LABEL: @cosf_copysign_arg_FMF(
+; ANY-NEXT:    [[COS:%.*]] = call reassoc nnan float @cosf(float [[X:%.*]])
+; ANY-NEXT:    ret float [[COS]]
+;
+  %copysign = tail call float @llvm.copysign.f32(float %x, float %y)
+  %r = call nnan reassoc float @cosf(float %copysign)
+  ret float %r
+}
+
 ; sin(-x) -> -sin(x);
 
 define double @sin_negated_arg(double %x) {