[Flang] Correct initial limit value in float min/maxloc reductions.

[davemgreen]

I was looking through to check whether Nan was being handled correctly, and couldn't work out why simple cases were behaving differently than they should. It turns out the initial limit values was backwards for minloc/maxloc reductions in general. This fixes that, introduced in #79469.

[llvmbot]

@llvm/pr-subscribers-flang-fir-hlfir

Author: David Green (davemgreen)

Changes

I was looking through to check whether Nan was being handled correctly, and couldn't work out why simple cases were behaving differently than they should. It turns out the initial limit values was backwards for minloc/maxloc reductions in general. This fixes that, introduced in #79469.

---

Full diff: https://github.com/llvm/llvm-project/pull/81260.diff

3 Files Affected:

• (modified) flang/lib/Optimizer/HLFIR/Transforms/OptimizedBufferization.cpp (+1-1)
• (modified) flang/test/HLFIR/maxloc-elemental.fir (+1)
• (modified) flang/test/HLFIR/minloc-elemental.fir (+1)

diff --git a/flang/lib/Optimizer/HLFIR/Transforms/OptimizedBufferization.cpp b/flang/lib/Optimizer/HLFIR/Transforms/OptimizedBufferization.cpp
index b1165a5ee19395..523671f0605f77 100644
--- a/flang/lib/Optimizer/HLFIR/Transforms/OptimizedBufferization.cpp
+++ b/flang/lib/Optimizer/HLFIR/Transforms/OptimizedBufferization.cpp
@@ -854,7 +854,7 @@ class MinMaxlocElementalConversion : public mlir::OpRewritePattern<Op> {
         const llvm::fltSemantics &sem = ty.getFloatSemantics();
         return builder.createRealConstant(
             loc, elementType,
-            llvm::APFloat::getLargest(sem, /*Negative=*/!isMax));
+            llvm::APFloat::getLargest(sem, /*Negative=*/isMax));
       }
       unsigned bits = elementType.getIntOrFloatBitWidth();
       int64_t limitInt =
diff --git a/flang/test/HLFIR/maxloc-elemental.fir b/flang/test/HLFIR/maxloc-elemental.fir
index 67cd9ee4bb75a7..b4a3ca0d86068f 100644
--- a/flang/test/HLFIR/maxloc-elemental.fir
+++ b/flang/test/HLFIR/maxloc-elemental.fir
@@ -110,6 +110,7 @@ func.func @_QPtest_float(%arg0: !fir.box<!fir.array<?xf32>> {fir.bindc_name = "a
   return
 }
 // CHECK-LABEL: _QPtest_float
+// CHECK:        %cst = arith.constant -3.40282347E+38 : f32
 // CHECK:        %[[V11:.*]] = fir.do_loop %arg3 = %c0 to %[[V10:.*]] step %c1 iter_args(%arg4 = %cst) -> (f32) {
 // CHECK-NEXT:     %[[V14:.*]] = arith.addi %arg3, %c1 : index
 // CHECK-NEXT:     %[[V15:.*]] = hlfir.designate %[[V1:.*]]#0 (%[[V14]])  : (!fir.box<!fir.array<?xf32>>, index) -> !fir.ref<f32>
diff --git a/flang/test/HLFIR/minloc-elemental.fir b/flang/test/HLFIR/minloc-elemental.fir
index cb483d51e05d13..5cc608b65be8bc 100644
--- a/flang/test/HLFIR/minloc-elemental.fir
+++ b/flang/test/HLFIR/minloc-elemental.fir
@@ -295,6 +295,7 @@ func.func @_QPtest_float(%arg0: !fir.box<!fir.array<?xf32>> {fir.bindc_name = "a
   return
 }
 // CHECK-LABEL: _QPtest_float
+// CHECK:        %cst = arith.constant 3.40282347E+38 : f32
 // CHECK:        %[[V11:.*]] = fir.do_loop %arg3 = %c0 to %[[V10:.*]] step %c1 iter_args(%arg4 = %cst) -> (f32) {
 // CHECK-NEXT:     %[[V14:.*]] = arith.addi %arg3, %c1 : index
 // CHECK-NEXT:     %[[V15:.*]] = hlfir.designate %[[V1:.*]]#0 (%[[V14]])  : (!fir.box<!fir.array<?xf32>>, index) -> !fir.ref<f32>

[kiranchandramohan]

LGTM.

[Leporacanthicus]

LGTM