Revert "ac: generate FMA for inexact instructions for radeonsi"

This reverts commit 4b9370cb0f.

Fixes: 4b9370cb0f
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3429

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6284>

.gitlab-ci/traces-radeonsi.yml

@@ -17,7 +17,7 @@ traces:
   - path: 0ad/0ad.trace
     expectations:
       - device: gl-radeonsi-stoney
-        checksum: bfd97a7190f2b9de24ddfd446fcc4850
+        checksum: c6261e56f37cc5d73b83d493561df646
   - path: pathfinder/demo.trace
     expectations:
       - device: gl-radeonsi-stoney
@@ -37,7 +37,7 @@ traces:
   - path: gputest/pixmark-piano.trace
     expectations:
       - device: gl-radeonsi-stoney
-        checksum: 061226c3fd179c611b8d60acaa44474f
+        checksum: a0e1d6358f76666603b08eab383af080
   - path: gputest/triangle.trace
     expectations:
       - device: gl-radeonsi-stoney
@@ -189,7 +189,7 @@ traces:
   - path: gputest/pixmark-piano.trace
     expectations:
       - device: gl-radeonsi-stoney
-        checksum: 061226c3fd179c611b8d60acaa44474f
+        checksum: a0e1d6358f76666603b08eab383af080
   - path: gputest/pixmark-volplosion.trace
     expectations:
       - device: gl-radeonsi-stoney
@@ -197,7 +197,7 @@ traces:
   - path: gputest/plot3d.trace
     expectations:
       - device: gl-radeonsi-stoney
-        checksum: 799ce7b2d8050d6ba2e3ae595cf8729e
+        checksum: fd367551aa74e2903e0590a893da01a6
   - path: gputest/tessmark.trace
     expectations:
       - device: gl-radeonsi-stoney

src/amd/llvm/ac_llvm_helper.cpp

@@ -114,11 +114,6 @@ LLVMBuilderRef ac_create_builder(LLVMContextRef ctx,
 		 */
 		flags.setAllowReciprocal(); /* arcp */
 
-		/* Allow floating-point contraction (e.g. fusing a multiply
-		 * followed by an addition into a fused multiply-and-add).
-		 */
-		flags.setAllowContract(); /* contract */
-
 		llvm::unwrap(builder)->setFastMathFlags(flags);
 		break;
 	}
@@ -126,32 +121,6 @@ LLVMBuilderRef ac_create_builder(LLVMContextRef ctx,
 	return builder;
 }
 
-/* Return the original state of inexact math. */
-bool ac_disable_inexact_math(LLVMBuilderRef builder)
-{
-	auto *b = llvm::unwrap(builder);
-	llvm::FastMathFlags flags = b->getFastMathFlags();
-
-	if (!flags.allowContract())
-		return false;
-
-	flags.setAllowContract(false);
-	b->setFastMathFlags(flags);
-	return true;
-}
-
-void ac_restore_inexact_math(LLVMBuilderRef builder, bool value)
-{
-	auto *b = llvm::unwrap(builder);
-	llvm::FastMathFlags flags = b->getFastMathFlags();
-
-	if (flags.allowContract() == value)
-		return;
-
-	flags.setAllowContract(value);
-	b->setFastMathFlags(flags);
-}
-
 LLVMTargetLibraryInfoRef
 ac_create_target_library_info(const char *triple)
 {

src/amd/llvm/ac_llvm_util.h

@@ -109,8 +109,6 @@ LLVMModuleRef ac_create_module(LLVMTargetMachineRef tm, LLVMContextRef ctx);
 
 LLVMBuilderRef ac_create_builder(LLVMContextRef ctx,
 				 enum ac_float_mode float_mode);
-bool ac_disable_inexact_math(LLVMBuilderRef builder);
-void ac_restore_inexact_math(LLVMBuilderRef builder, bool value);
 
 void
 ac_llvm_add_target_dep_function_attr(LLVMValueRef F,

src/amd/llvm/ac_nir_to_llvm.c

@@ -601,10 +601,6 @@ static void visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
 	unsigned num_components = instr->dest.dest.ssa.num_components;
 	unsigned src_components;
 	LLVMTypeRef def_type = get_def_type(ctx, &instr->dest.dest.ssa);
-	bool saved_inexact = false;
-
-	if (instr->exact)
-		saved_inexact = ac_disable_inexact_math(ctx->ac.builder);
 
 	assert(nir_op_infos[instr->op].num_inputs <= ARRAY_SIZE(src));
 	switch (instr->op) {
@@ -1192,9 +1188,6 @@ static void visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
 		result = ac_to_integer_or_pointer(&ctx->ac, result);
 		ctx->ssa_defs[instr->dest.dest.ssa.index] = result;
 	}
-
-	if (instr->exact)
-		ac_restore_inexact_math(ctx->ac.builder, saved_inexact);
 }
 
 static void visit_load_const(struct ac_nir_context *ctx,