[llvm] 6e88276 - Pre-commit a min/max idiom breakage test for D149918

[Amara Emerson via llvm-commits]

Author: Amara Emerson
Date: 2023-05-24T15:02:40-07:00
New Revision: 6e88276411c69e194c2f89270a18852a85fc79a7

URL: https://github.com/llvm/llvm-project/commit/6e88276411c69e194c2f89270a18852a85fc79a7
DIFF: https://github.com/llvm/llvm-project/commit/6e88276411c69e194c2f89270a18852a85fc79a7.diff

LOG: Pre-commit a min/max idiom breakage test for D149918

Added: 
    llvm/test/Transforms/InstCombine/ashr-icmp-minmax-idiom-break.ll

Modified: 
    

Removed: 
    


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diff  --git a/llvm/test/Transforms/InstCombine/ashr-icmp-minmax-idiom-break.ll b/llvm/test/Transforms/InstCombine/ashr-icmp-minmax-idiom-break.ll
new file mode 100644
index 000000000000..a539b9136689
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/ashr-icmp-minmax-idiom-break.ll
@@ -0,0 +1,23 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+; This test is pre-committed to show sub-optimal codegen due to
+; min/max idiom breakage. On AArch64, these constants are also expensive to materialize,
+; and therefore generate poor code vs maintaining the min/max idiom.
+
+define i64 @dont_break_minmax_i64(i64 %conv, i64 %conv2) {
+; CHECK-LABEL: define i64 @dont_break_minmax_i64
+; CHECK-SAME: (i64 [[CONV:%.*]], i64 [[CONV2:%.*]]) {
+; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i64 [[CONV]], [[CONV2]]
+; CHECK-NEXT:    [[SHR:%.*]] = ashr i64 [[MUL]], 4
+; CHECK-NEXT:    [[CMP4_I:%.*]] = icmp slt i64 [[MUL]], 5579712
+; CHECK-NEXT:    [[SPEC_SELECT_I:%.*]] = select i1 [[CMP4_I]], i64 [[SHR]], i64 348731
+; CHECK-NEXT:    ret i64 [[SPEC_SELECT_I]]
+;
+  %mul = mul nsw i64 %conv, %conv2
+  %shr = ashr i64 %mul, 4
+  %cmp4.i = icmp sgt i64 %shr, 348731
+  %switch.i = icmp ult i1 %cmp4.i, true
+  %spec.select.i = select i1 %switch.i, i64 %shr, i64 348731
+  ret i64 %spec.select.i
+}