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From: Daniel Golle <daniel@makrotopia.org>
Subject: [PATCH] JavaScriptCore: declare BBQJIT ScratchScope for non-X86/non-ARM64 archs
WasmBBQJIT64.cpp's addSIMDShuffle and addSIMDShift declare a ScratchScope
named "scratches" only inside #if CPU(X86_64) / #elif CPU(ARM64), then
reference that name from "if constexpr (isX86())" blocks and other code
in the same function. In a non-template function, "if constexpr" does not
discard the false branch from name lookup (C++17 [stmt.if]p2), so on any
architecture not in that list the build fails with:
error: 'scratches' was not declared in this scope
Add an #else branch in both functions declaring a ScratchScope with the
same template arity as the X86 path. wasm SIMD is gated off at runtime
on RISCV64 via Options::useWasmSIMD = false, so neither function is
reached and the new scratches declaration is unused at run time; it
only exists so the function bodies parse on RISCV64.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
--- a/Source/JavaScriptCore/wasm/WasmBBQJIT64.cpp
+++ b/Source/JavaScriptCore/wasm/WasmBBQJIT64.cpp
@@ -3442,6 +3442,11 @@ void BBQJIT::notifyFunctionUsesSIMD()
clobber(ARM64Registers::q28);
clobber(ARM64Registers::q29);
ScratchScope<0, 0> scratches(*this, Location::fromFPR(ARM64Registers::q28), Location::fromFPR(ARM64Registers::q29));
+#else
+ // Other architectures (e.g. RISCV64) have no wasm SIMD codegen and
+ // never reach this function at runtime (useWasmSIMD is forced off).
+ // Declare scratches so the if-constexpr(isX86()) block below parses.
+ ScratchScope<0, 1> scratches(*this);
#endif
Location aLocation = loadIfNecessary(a);
Location bLocation = loadIfNecessary(b);
@@ -3497,6 +3502,11 @@ void BBQJIT::notifyFunctionUsesSIMD()
// Clobber and preserve RCX on x86, since we need it to do shifts.
clobber(shiftRCX);
ScratchScope<2, 2> scratches(*this, Location::fromGPR(shiftRCX));
+#elif !CPU(ARM64)
+ // RISCV64 / other archs: no wasm SIMD codegen exists; this function
+ // is unreachable at runtime via useWasmSIMD = false. Declare a
+ // ScratchScope so the X86-only sub-block below still parses.
+ ScratchScope<2, 2> scratches(*this);
#endif
Location srcLocation = loadIfNecessary(src);
Location shiftLocation;
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