[clang] [flang] [Flang] Add -ffast-real-mod back for further control of MOD optimizations (PR #167118)

[Michael Klemm via cfe-commits]

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@@ -1,24 +1,24 @@
-! RUN: %flang_fc1 -ffast-math -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK%if target=x86_64{{.*}} %{,CHECK-KIND10%}%if flang-supports-f128-math %{,CHECK-KIND16%}
+! RUN: %flang_fc1 -ffast-real-mod -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK-FRM%if target=x86_64{{.*}} %{,CHECK-FRM-KIND10%}%if flang-supports-f128-math %{,CHECK-FRM-KIND16%}
+! RUN: %flang_fc1 -ffast-math -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK-FRM%if target=x86_64{{.*}} %{,CHECK-FRM-KIND10%}%if flang-supports-f128-math %{,CHECK-FRM-KIND16%}
 ! RUN: %flang_fc1 -ffast-math -fno-fast-real-mod -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK-NFRM%if target=x86_64{{.*}} %{,CHECK-NFRM-KIND10%}%if flang-supports-f128-math %{,CHECK-NFRM-KIND16%}
 
-! TODO: check line that fir.fast_real_mod is not there
-! CHECK-NFRM: module attributes {{{.*}}fir.no_fast_real_mod = true{{.*}}}
+! CHECK,CHECK-FRM: module attributes {{{.*}}fir.fast_real_mod = true{{.*}}}
 
 ! CHECK-LABEL: @_QPmod_real4
 subroutine mod_real4(r, a, p)
     implicit none
     real(kind=4) :: r, a, p
-! CHECK: %[[A:.*]] = fir.declare{{.*}}a"
-! CHECK: %[[P:.*]] = fir.declare{{.*}}p"
-! CHECK: %[[R:.*]] = fir.declare{{.*}}r"
-! CHECK: %[[A_LOAD:.*]] = fir.load %[[A]]
-! CHECK: %[[P_LOAD:.*]] = fir.load %[[P]]
-! CHECK: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<fast> : f32
-! CHECK: %[[CV1:.*]] = fir.convert %[[DIV]] : (f32) -> si32
-! CHECK: %[[CV2:.*]] = fir.convert %[[CV1]] : (si32) -> f32
-! CHECK: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<fast> : f32
-! CHECK: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<fast> : f32
-! CHECK: fir.store %[[SUB]] to %[[R]] : !fir.ref<f32>
+! CHECK-FRM: %[[A:.*]] = fir.declare{{.*}}a"
+! CHECK-FRM: %[[P:.*]] = fir.declare{{.*}}p"
+! CHECK-FRM: %[[R:.*]] = fir.declare{{.*}}r"
+! CHECK-FRM: %[[A_LOAD:.*]] = fir.load %[[A]]
+! CHECK-FRM: %[[P_LOAD:.*]] = fir.load %[[P]]
+! CHECK-FRM: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<{{.*}}> : f32
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mjklemm wrote:

When `-ffast-math` is active, the `fastmath` tag is `fast` while with only `-ffast-real-mod` it remains at `contract`.  I can certainly split this into two separate checks if you prefer it that way.

https://github.com/llvm/llvm-project/pull/167118