[llvm] [CVP][SCCP] Add support for `uitofp nneg` (PR #86154)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,203 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=correlated-propagation -S | FileCheck %s
+
+declare void @use.f32(float)
+
+define void @test1_fptosi(i32 %n) {
+; CHECK-LABEL: @test1_fptosi(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_COND:%.*]]
+; CHECK:       for.cond:
+; CHECK-NEXT:    [[A:%.*]] = phi i32 [ [[N:%.*]], [[ENTRY:%.*]] ], [ [[EXT:%.*]], [[FOR_BODY:%.*]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A]], -1
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[EXT_WIDE:%.*]] = uitofp nneg i32 [[A]] to float
+; CHECK-NEXT:    call void @use.f32(float [[EXT_WIDE]])
+; CHECK-NEXT:    [[EXT]] = fptosi float [[EXT_WIDE]] to i32
+; CHECK-NEXT:    br label [[FOR_COND]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.cond
+
+for.cond:  ; preds = %for.body, %entry
+  %a = phi i32 [ %n, %entry ], [ %ext, %for.body ]
+  %cmp = icmp sgt i32 %a, -1
+  br i1 %cmp, label %for.body, label %for.end
+
+for.body:  ; preds = %for.cond
+  %ext.wide = sitofp i32 %a to float
+  call void @use.f32(float %ext.wide)
+  %ext = fptosi float %ext.wide to i32
+  br label %for.cond
+
+for.end:  ; preds = %for.cond
+  ret void
+}
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nikic wrote:

These tests look unnecessarily complicated -- can we just assert that %a is non-negative? Or at least drop the loop around it?

https://github.com/llvm/llvm-project/pull/86154