[llvm] [BPF] Allow libcalls behind a feature gate (PR #168442)

[Lucas Ste via llvm-commits]

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@@ -0,0 +1,39 @@
+; RUN: llc -march=bpfel -mattr=+allow-builtin-calls < %s | FileCheck %s
+;
+; C code for this test case:
+;
+; long func(long a, long b) {
+;     long x;
+;     return __builtin_mul_overflow(a, b, &x);
+; }
+
+
+declare { i64, i1 } @llvm.smul.with.overflow.i64(i64, i64)
+
+define noundef range(i64 0, 2) i64 @func(i64 noundef %a, i64 noundef %b) local_unnamed_addr {
+entry:
+  %0 = tail call { i64, i1 } @llvm.smul.with.overflow.i64(i64 %a, i64 %b)
+  %1 = extractvalue { i64, i1 } %0, 1
+  %conv = zext i1 %1 to i64
+  ret i64 %conv
+}
+
+; CHECK-LABEL: func
+; CHECK: r4 = r2
+; CHECK: r2 = r1
+; CHECK: r3 = r2
+; CHECK: r3 s>>= 63
+; CHECK: r5 = r4
+; CHECK: r5 s>>= 63
+; CHECK: r1 = r10
+; CHECK: r1 += -16
+; CHECK: call __multi3
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LucasSte wrote:

Is this message clear for the commit?

https://github.com/llvm/llvm-project/pull/168442