[clang] [clang][CodeGen] Propagate pragma set fast-math flags to floating point builtins (PR #90377)

[Zahira Ammarguellat via cfe-commits]

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@@ -0,0 +1,28 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 4
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -O3 -emit-llvm -o - %s \
+// RUN: | FileCheck -check-prefix=CHECK %s
+
+// Reproducer for issue #87758
+// The testcase below verifies that the "fast" flag are set on the calls.
+
+float sqrtf(float x);
+float powf(float x, float y);
+float fmaf(float x, float y, float z);
+
+#pragma float_control(push)
+#pragma float_control(precise, off)
+// CHECK-LABEL: define dso_local float @fp_precise_libm_calls(
+// CHECK-SAME: float noundef [[A:%.*]], float noundef [[B:%.*]], float noundef [[C:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[TMP0:%.*]] = tail call fast float @llvm.sqrt.f32(float [[A]])
+// CHECK-NEXT:    [[TMP1:%.*]] = tail call fast float @llvm.pow.f32(float [[TMP0]], float [[B]])
+// CHECK-NEXT:    [[TMP2:%.*]] = tail call fast float @llvm.fma.f32(float [[TMP1]], float [[B]], float [[C]])
+// CHECK-NEXT:    ret float [[TMP2]]
+//
+float fp_precise_libm_calls(float a, float b, float c) {
+  a = sqrtf(a);
+  a = powf(a,b);
+  a = fmaf(a,b,c);
+  return a;
+}
+#pragma float_control(pop)
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zahiraam wrote:

You could also use the same test with `#pragma float_control(precise,on)` and confirm that the fast flags are not set. 

https://github.com/llvm/llvm-project/pull/90377