[InstCombine] add test for failed libfunction prototype matching; NFC

llvm-svn: 363291

llvm/test/Transforms/InstCombine/sqrt-nofast.ll

@@ -1,8 +1,16 @@
-; Check that we skip transformations if the attribute unsafe-fp-math
-; is not set.
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 
+; Check that we skip transformations if the attribute unsafe-fp-math
+; is not set.
+
 define float @mysqrt(float %x, float %y) #0 {
+; CHECK-LABEL: @mysqrt(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[MUL:%.*]] = fmul fast float [[X:%.*]], [[X]]
+; CHECK-NEXT:    [[TMP0:%.*]] = call float @llvm.sqrt.f32(float [[MUL]])
+; CHECK-NEXT:    ret float [[TMP0]]
+;
 entry:
   %x.addr = alloca float, align 4
   %y.addr = alloca float, align 4
@@ -17,9 +25,19 @@ entry:
 
 declare float @llvm.sqrt.f32(float) #1
 
-; CHECK: define float @mysqrt(float %x, float %y) {
-; CHECK: entry:
-; CHECK:   %mul = fmul fast float %x, %x
-; CHECK:   %0 = call float @llvm.sqrt.f32(float %mul)
-; CHECK:   ret float %0
-; CHECK: }
+; FIXME:
+; This is a function called "sqrtf", but its type is double.
+; Assume it is a user function rather than a libm function,
+; so don't transform it.
+
+define double @fake_sqrt(double %a, double %b) {
+; CHECK-LABEL: @fake_sqrt(
+; CHECK-NEXT:    [[FABS:%.*]] = call fast double @llvm.fabs.f64(double [[A:%.*]])
+; CHECK-NEXT:    ret double [[FABS]]
+;
+  %c = fmul fast double %a, %a
+  %e = call fast double @sqrtf(double %c) readnone
+  ret double %e
+}
+
+declare double @sqrtf(double) readnone ; This is not the 'sqrt' you're looking for.