[clang] [llvm] [ARM] enable FENV_ACCESS pragma support for hard-float targets (PR #137101)

[Erik Enikeev via llvm-commits]

https://github.com/Varnike updated https://github.com/llvm/llvm-project/pull/137101

>From 1b3f48acc5a409648fa0ec374c16411df754ce6d Mon Sep 17 00:00:00 2001
From: Erik Enikeev <evonatarius at gmail.com>
Date: Mon, 9 Jun 2025 12:08:15 -0400
Subject: [PATCH 1/2] Added support for FENV_ACCESS pragma on hard-float ARM
 platforms. Also changes were made to clang/test/Parser/pragma-fp-warn.c so
 that for thumbv7a only the soft-float-abi target case is checked.

---
 clang/lib/Basic/Targets/ARM.cpp    | 2 ++
 clang/test/Parser/pragma-fp-warn.c | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Basic/Targets/ARM.cpp b/clang/lib/Basic/Targets/ARM.cpp
index 65d4ed1e96540..ec86d41833c9b 100644
--- a/clang/lib/Basic/Targets/ARM.cpp
+++ b/clang/lib/Basic/Targets/ARM.cpp
@@ -362,6 +362,8 @@ ARMTargetInfo::ARMTargetInfo(const llvm::Triple &Triple,
                            : "\01mcount";
 
   SoftFloatABI = llvm::is_contained(Opts.FeaturesAsWritten, "+soft-float-abi");
+  if (!SoftFloatABI)
+    HasStrictFP = true;
 }
 
 StringRef ARMTargetInfo::getABI() const { return ABI; }
diff --git a/clang/test/Parser/pragma-fp-warn.c b/clang/test/Parser/pragma-fp-warn.c
index c52bd4e4805ab..f743cb87997dc 100644
--- a/clang/test/Parser/pragma-fp-warn.c
+++ b/clang/test/Parser/pragma-fp-warn.c
@@ -1,6 +1,6 @@
 
 // RUN: %clang_cc1 -triple wasm32 -fsyntax-only -Wno-unknown-pragmas -Wignored-pragmas -verify %s
-// RUN: %clang_cc1 -triple thumbv7 -fsyntax-only -Wno-unknown-pragmas -Wignored-pragmas -verify %s
+// RUN: %clang_cc1 -triple thumbv7 -fsyntax-only -target-feature +soft-float-abi  -Wno-unknown-pragmas -Wignored-pragmas -verify %s
 // RUN: %clang_cc1 -DEXPOK -triple aarch64 -fsyntax-only -Wno-unknown-pragmas -Wignored-pragmas -verify %s
 // RUN: %clang_cc1 -DEXPOK -triple x86_64 -fsyntax-only -Wno-unknown-pragmas -Wignored-pragmas -verify %s
 // RUN: %clang_cc1 -DEXPOK -triple systemz -fsyntax-only -Wno-unknown-pragmas -Wignored-pragmas -verify %s

>From 0231231d5c373f2e4e5b42a59e8e1fc39388b61f Mon Sep 17 00:00:00 2001
From: Erik Enikeev <evonatarius at gmail.com>
Date: Mon, 9 Jun 2025 11:11:52 -0400
Subject: [PATCH 2/2] Enable STRICT_FDIV support for ARM

---
 llvm/lib/Target/ARM/ARMISelLowering.cpp |  4 ++++
 llvm/lib/Target/ARM/ARMInstrVFP.td      | 12 ++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index fb72bab03e750..c875a7ddd4430 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -882,6 +882,10 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM_,
   }
 
   if (Subtarget->hasNEON()) {
+    // STRICT_FDIV is legal for f32 and f64
+    setOperationAction(ISD::STRICT_FDIV, MVT::f32, Legal);
+    setOperationAction(ISD::STRICT_FDIV, MVT::f64, Legal);
+
     // The same with v4f32. But keep in mind that vadd, vsub, vmul are natively
     // supported for v4f32.
     setOperationAction(ISD::FSQRT, MVT::v4f32, Expand);
diff --git a/llvm/lib/Target/ARM/ARMInstrVFP.td b/llvm/lib/Target/ARM/ARMInstrVFP.td
index 31650e0137beb..e52c586bd8088 100644
--- a/llvm/lib/Target/ARM/ARMInstrVFP.td
+++ b/llvm/lib/Target/ARM/ARMInstrVFP.td
@@ -485,25 +485,25 @@ def VSUBH  : AHbI<0b11100, 0b11, 1, 0,
                   [(set (f16 HPR:$Sd), (fsub (f16 HPR:$Sn), (f16 HPR:$Sm)))]>,
             Sched<[WriteFPALU32]>;
 
-let TwoOperandAliasConstraint = "$Dn = $Dd" in
+let TwoOperandAliasConstraint = "$Dn = $Dd", mayRaiseFPException = 1, Uses = [FPSCR] in
 def VDIVD  : ADbI<0b11101, 0b00, 0, 0,
                   (outs DPR:$Dd), (ins DPR:$Dn, DPR:$Dm),
                   IIC_fpDIV64, "vdiv", ".f64\t$Dd, $Dn, $Dm",
-                  [(set DPR:$Dd, (fdiv DPR:$Dn, (f64 DPR:$Dm)))]>,
+                  [(set DPR:$Dd, (any_fdiv DPR:$Dn, (f64 DPR:$Dm)))]>,
              Sched<[WriteFPDIV64]>;
 
-let TwoOperandAliasConstraint = "$Sn = $Sd" in
+let TwoOperandAliasConstraint = "$Sn = $Sd", mayRaiseFPException = 1, Uses = [FPSCR] in
 def VDIVS  : ASbI<0b11101, 0b00, 0, 0,
                   (outs SPR:$Sd), (ins SPR:$Sn, SPR:$Sm),
                   IIC_fpDIV32, "vdiv", ".f32\t$Sd, $Sn, $Sm",
-                  [(set SPR:$Sd, (fdiv SPR:$Sn, SPR:$Sm))]>,
+                  [(set SPR:$Sd, (any_fdiv SPR:$Sn, SPR:$Sm))]>,
              Sched<[WriteFPDIV32]>;
 
-let TwoOperandAliasConstraint = "$Sn = $Sd" in
+let TwoOperandAliasConstraint = "$Sn = $Sd", mayRaiseFPException = 1, Uses = [FPSCR]  in
 def VDIVH  : AHbI<0b11101, 0b00, 0, 0,
                   (outs HPR:$Sd), (ins HPR:$Sn, HPR:$Sm),
                   IIC_fpDIV16, "vdiv", ".f16\t$Sd, $Sn, $Sm",
-                  [(set (f16 HPR:$Sd), (fdiv (f16 HPR:$Sn), (f16 HPR:$Sm)))]>,
+                  [(set (f16 HPR:$Sd), (any_fdiv (f16 HPR:$Sn), (f16 HPR:$Sm)))]>,
              Sched<[WriteFPDIV32]>;
 
 let TwoOperandAliasConstraint = "$Dn = $Dd" in