[RISCV] Support svukte extension (#115657)

This is the extension for "Address-Independent Latency of User-Mode
Faults to Supervisor Addresses".
Spec: riscv/riscv-isa-manual#1564,
https://lf-riscv.atlassian.net/browse/RVS-2977
The spec states that the `svukte` depends on `sv39`, but we don't have
`sv39` yet, so I didn't add it to the implied list.

Author: 4vtomat

clang/test/Driver/print-supported-extensions-riscv.c

@@ -187,6 +187,7 @@
 // CHECK-NEXT:     zvkgs                0.7       'Zvkgs' (Vector-Scalar GCM instructions for Cryptography)
 // CHECK-NEXT:     smctr                1.0       'Smctr' (Control Transfer Records Machine Level)
 // CHECK-NEXT:     ssctr                1.0       'Ssctr' (Control Transfer Records Supervisor Level)
+// CHECK-NEXT:     svukte               0.3       'Svukte' (Address-Independent Latency of User-Mode Faults to Supervisor Addresses)
 // CHECK-EMPTY:
 // CHECK-NEXT: Supported Profiles
 // CHECK-NEXT:     rva20s64

clang/test/Preprocessor/riscv-target-features.c

@@ -1811,6 +1811,14 @@
 // RUN:   -o - | FileCheck --check-prefix=CHECK-SSCTR-EXT %s
 // CHECK-SSCTR-EXT: __riscv_ssctr 1000000{{$}}
 
+// RUN: %clang --target=riscv32 -menable-experimental-extensions \
+// RUN:   -march=rv32i_svukte0p3 -E -dM %s \
+// RUN:   -o - | FileCheck --check-prefix=CHECK-SVUKTE-EXT %s
+// RUN: %clang --target=riscv64 -menable-experimental-extensions \
+// RUN:   -march=rv64i_svukte0p3 -E -dM %s \
+// RUN:   -o - | FileCheck --check-prefix=CHECK-SVUKTE-EXT %s
+// CHECK-SVUKTE-EXT: __riscv_svukte 3000{{$}}
+
 // Misaligned
 
 // RUN: %clang --target=riscv32-unknown-linux-gnu -march=rv32i -E -dM %s \

llvm/docs/RISCVUsage.rst

@@ -329,6 +329,9 @@ The primary goal of experimental support is to assist in the process of ratifica
 ``experimental-smctr``, ``experimental-ssctr``
   LLVM implements the `1.0-rc3 specification <https://github.com/riscv/riscv-control-transfer-records/releases/tag/v1.0_rc3>`__.
 
+``experimental-svukte``
+  LLVM implements the `0.3 draft specification <https://github.com/riscv/riscv-isa-manual/pull/1564>`__.
+
 To use an experimental extension from `clang`, you must add `-menable-experimental-extensions` to the command line, and specify the exact version of the experimental extension you are using.  To use an experimental extension with LLVM's internal developer tools (e.g. `llc`, `llvm-objdump`, `llvm-mc`), you must prefix the extension name with `experimental-`.  Note that you don't need to specify the version with internal tools, and shouldn't include the `experimental-` prefix with `clang`.
 
 Vendor Extensions

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -1059,6 +1059,10 @@ def FeatureStdExtSha
                       FeatureStdExtShvstvala, FeatureStdExtShtvala, FeatureStdExtShvstvecd,
                       FeatureStdExtShvsatpa, FeatureStdExtShgatpa]>;
 
+def FeatureStdExtSvukte
+    : RISCVExperimentalExtension<"svukte", 0, 3,
+                                 "'Svukte' (Address-Independent Latency of User-Mode Faults to Supervisor Addresses)">;
+
 // Pointer Masking extensions
 
 // A supervisor-level extension that provides pointer masking for the next lower

llvm/test/CodeGen/RISCV/attributes.ll

@@ -62,6 +62,7 @@
 ; RUN: llc -mtriple=riscv32 -mattr=+svbare %s -o - | FileCheck --check-prefixes=CHECK,RV32SVBARE %s
 ; RUN: llc -mtriple=riscv32 -mattr=+svnapot %s -o - | FileCheck --check-prefixes=CHECK,RV32SVNAPOT %s
 ; RUN: llc -mtriple=riscv32 -mattr=+svpbmt %s -o - | FileCheck --check-prefixes=CHECK,RV32SVPBMT %s
+; RUN: llc -mtriple=riscv32 -mattr=+experimental-svukte %s -o - | FileCheck --check-prefixes=CHECK,RV32SVUKTE %s
 ; RUN: llc -mtriple=riscv32 -mattr=+svvptc %s -o - | FileCheck --check-prefixes=CHECK,RV32SVVPTC %s
 ; RUN: llc -mtriple=riscv32 -mattr=+svinval %s -o - | FileCheck --check-prefixes=CHECK,RV32SVINVAL %s
 ; RUN: llc -mtriple=riscv32 -mattr=+xcvalu %s -o - | FileCheck --check-prefix=RV32XCVALU %s
@@ -205,6 +206,7 @@
 ; RUN: llc -mtriple=riscv64 -mattr=+svbare %s -o - | FileCheck --check-prefixes=CHECK,RV64SVBARE %s
 ; RUN: llc -mtriple=riscv64 -mattr=+svnapot %s -o - | FileCheck --check-prefixes=CHECK,RV64SVNAPOT %s
 ; RUN: llc -mtriple=riscv64 -mattr=+svpbmt %s -o - | FileCheck --check-prefixes=CHECK,RV64SVPBMT %s
+; RUN: llc -mtriple=riscv64 -mattr=+experimental-svukte %s -o - | FileCheck --check-prefixes=CHECK,RV64SVUKTE %s
 ; RUN: llc -mtriple=riscv64 -mattr=+svvptc %s -o - | FileCheck --check-prefixes=CHECK,RV64SVVPTC %s
 ; RUN: llc -mtriple=riscv64 -mattr=+svinval %s -o - | FileCheck --check-prefixes=CHECK,RV64SVINVAL %s
 ; RUN: llc -mtriple=riscv64 -mattr=+xventanacondops %s -o - | FileCheck --check-prefixes=CHECK,RV64XVENTANACONDOPS %s
@@ -364,6 +366,7 @@
 ; RV32SVBARE: .attribute 5, "rv32i2p1_svbare1p0"
 ; RV32SVNAPOT: .attribute 5, "rv32i2p1_svnapot1p0"
 ; RV32SVPBMT: .attribute 5, "rv32i2p1_svpbmt1p0"
+; RV32SVUKTE: .attribute 5, "rv32i2p1_svukte0p3"
 ; RV32SVVPTC: .attribute 5, "rv32i2p1_svvptc1p0"
 ; RV32SVINVAL: .attribute 5, "rv32i2p1_svinval1p0"
 ; RV32XCVALU: .attribute 5, "rv32i2p1_xcvalu1p0"
@@ -509,6 +512,7 @@
 ; RV64SVBARE: .attribute 5, "rv64i2p1_svbare1p0"
 ; RV64SVNAPOT: .attribute 5, "rv64i2p1_svnapot1p0"
 ; RV64SVPBMT: .attribute 5, "rv64i2p1_svpbmt1p0"
+; RV64SVUKTE: .attribute 5, "rv64i2p1_svukte0p3"
 ; RV64SVVPTC: .attribute 5, "rv64i2p1_svvptc1p0"
 ; RV64SVINVAL: .attribute 5, "rv64i2p1_svinval1p0"
 ; RV64XVENTANACONDOPS: .attribute 5, "rv64i2p1_xventanacondops1p0"

llvm/test/MC/RISCV/attribute-arch.s

@@ -381,6 +381,9 @@
 .attribute arch, "rv32i_svbare1p0"
 # CHECK: attribute      5, "rv32i2p1_svbare1p0"
 
+.attribute arch, "rv32i_svukte0p3"
+# CHECK: attribute      5, "rv32i2p1_svukte0p3"
+
 .attribute arch, "rv32i_svvptc1p0"
 # CHECK: attribute      5, "rv32i2p1_svvptc1p0"
 

llvm/unittests/TargetParser/RISCVISAInfoTest.cpp

@@ -1103,6 +1103,7 @@ Experimental extensions
     zvkgs                0.7
     smctr                1.0
     ssctr                1.0
+    svukte               0.3
 
 Supported Profiles
     rva20s64