[llvm] [ValueTracking] Compute knownbits from known fp classes (PR #86409)

[Matt Arsenault via llvm-commits]

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@@ -483,5 +483,145 @@ if.else:
   ret i64 13
 }
 
+define i1 @test_sign_pos(float %x) {
+; CHECK-LABEL: @test_sign_pos(
+; CHECK-NEXT:    ret i1 true
+;
+  %fabs = call float @llvm.fabs.f32(float %x)
+  %y = bitcast float %fabs to i32
+  %sign = icmp sgt i32 %y, -1
+  ret i1 %sign
+}
+
+define i1 @test_sign_neg(float %x) {
+; CHECK-LABEL: @test_sign_neg(
+; CHECK-NEXT:    ret i1 true
+;
+  %fabs = call float @llvm.fabs.f32(float %x)
+  %fnabs = fneg float %fabs
+  %y = bitcast float %fnabs to i32
+  %sign = icmp slt i32 %y, 0
+  ret i1 %sign
+}
+
+define <2 x i1> @test_sign_pos_vec(<2 x float> %x) {
+; CHECK-LABEL: @test_sign_pos_vec(
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
+;
+  %fabs = call <2 x float> @llvm.fabs.v2f32(<2 x float> %x)
+  %y = bitcast <2 x float> %fabs to <2 x i32>
+  %sign = icmp slt <2 x i32> %y, zeroinitializer
+  ret <2 x i1> %sign
+}
+
+define i32 @test_inf_only(float nofpclass(nan sub norm zero) %x) {
+; CHECK-LABEL: @test_inf_only(
+; CHECK-NEXT:    ret i32 2130706432
+;
+  %y = bitcast float %x to i32
+  %and = and i32 %y, 2147483647
+  ret i32 %and
+}
+
+define i32 @test_zero_only(float nofpclass(nan sub norm inf) %x) {
+; CHECK-LABEL: @test_zero_only(
+; CHECK-NEXT:    ret i32 0
+;
+  %y = bitcast float %x to i32
+  %and = and i32 %y, 2147483647
+  ret i32 %and
+}
+
+define i32 @test_inf_nan_only(float nofpclass(sub norm zero) %x) {
+; CHECK-LABEL: @test_inf_nan_only(
+; CHECK-NEXT:    ret i32 2130706432
+;
+  %y = bitcast float %x to i32
+  %and = and i32 %y, 2130706432
+  ret i32 %and
+}
+
+define i32 @test_sub_zero_only(float nofpclass(nan norm inf) %x) {
+; CHECK-LABEL: @test_sub_zero_only(
+; CHECK-NEXT:    ret i32 0
+;
+  %y = bitcast float %x to i32
+  %and = and i32 %y, 2130706432
+  ret i32 %and
+}
+
+define i32 @test_inf_zero_only(float nofpclass(nan norm sub) %x) {
+; CHECK-LABEL: @test_inf_zero_only(
+; CHECK-NEXT:    ret i32 0
+;
+  %y = bitcast float %x to i32
+  %and = and i32 %y, 16777215
+  ret i32 %and
+}
+
+define i1 @test_simplify_icmp(i32 %x) {
+; CHECK-LABEL: @test_simplify_icmp(
+; CHECK-NEXT:    ret i1 false
+;
+  %conv.i.i = uitofp i32 %x to double
+  %3 = bitcast double %conv.i.i to i64
----------------
arsenm wrote:

Use named values 

https://github.com/llvm/llvm-project/pull/86409