Mesa (master): ac/nir: fix out-of-bound access when loading constants from global

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Module: Mesa
Branch: master
Commit: a0f1a5fa051786c16de6f0062771051f8565daec
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=a0f1a5fa051786c16de6f0062771051f8565daec

Author: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Date:   Tue Dec 10 17:46:26 2019 +0100

ac/nir: fix out-of-bound access when loading constants from global

Global load/store instructions can't know if the offset is
out-of-bound because they don't use descriptors (no range).

Fix this by clamping the offset for arrays that are indexed
with a non-constant offset that's greater or equal to the array
size.

This fixes VM faults and GPU hangs with Dead Rising 4.

Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/2148
Fixes: 71a67942003 ("ac/nir: Enable nir_opt_large_constants")
Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

---

 src/amd/llvm/ac_nir_to_llvm.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/amd/llvm/ac_nir_to_llvm.c b/src/amd/llvm/ac_nir_to_llvm.c
index 4c8216dbe73..d69b8c90238 100644
--- a/src/amd/llvm/ac_nir_to_llvm.c
+++ b/src/amd/llvm/ac_nir_to_llvm.c
@@ -3758,11 +3758,21 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
 		break;
 	}
 	case nir_intrinsic_load_constant: {
+		unsigned base = nir_intrinsic_base(instr);
+		unsigned range = nir_intrinsic_range(instr);
+
 		LLVMValueRef offset = get_src(ctx, instr->src[0]);
-		LLVMValueRef base = LLVMConstInt(ctx->ac.i32,
-						 nir_intrinsic_base(instr),
-						 false);
-		offset = LLVMBuildAdd(ctx->ac.builder, offset, base, "");
+		offset = LLVMBuildAdd(ctx->ac.builder, offset,
+				      LLVMConstInt(ctx->ac.i32, base, false), "");
+
+		/* Clamp the offset to avoid out-of-bound access because global
+		 * instructions can't handle them.
+		 */
+		LLVMValueRef size = LLVMConstInt(ctx->ac.i32, base + range, false);
+		LLVMValueRef cond = LLVMBuildICmp(ctx->ac.builder, LLVMIntULT,
+						  offset, size, "");
+		offset = LLVMBuildSelect(ctx->ac.builder, cond, offset, size, "");
+
 		LLVMValueRef ptr = ac_build_gep0(&ctx->ac, ctx->constant_data,
 						 offset);
 		LLVMTypeRef comp_type =